• 126 can be written using four 4's:

126 has 12 divisors (see below), whose sum is σ = 312. Its totient is φ = 36.

The previous prime is 113. The next prime is 127. The reversal of 126 is 621.

126 = 4^{2} + 5^{2} + ... + 7^{2}.

126 is nontrivially palindromic in base 5 and base 13.

It is a Cunningham number, because it is equal to 5^{3}+1.

126 is a nontrivial binomial coefficient, being equal to C(9, 4).

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a nude number because it is divisible by every one of its digits.

It is an Ulam number.

It is one of the 548 Lynch-Bell numbers.

Its product of digits (12) is a multiple of the sum of its prime divisors (12).

126 is a nontrivial repdigit in base 13.

It is a plaindrome in base 10, base 13 and base 16.

It is a nialpdrome in base 2, base 6, base 12, base 13, base 14 and base 15.

It is a zygodrome in base 13.

It is a congruent number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 15 + ... + 21.

It is an arithmetic number, because the mean of its divisors is an integer number (26).

126 is a Friedman number, since it can be written as 21*6, using all its digits and the basic arithmetic operations.

126 is the 6-th decagonal number.

It is a practical number, because each smaller number is the sum of distinct divisors of 126, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (156).

126 is an abundant number, since it is smaller than the sum of its proper divisors (186).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

126 is a wasteful number, since it uses less digits than its factorization.

With its predecessor (125) it forms a Ruth-Aaron pair, since the sum of their prime factors is the same (15).

126 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15 (or 12 counting only the distinct ones).

The product of its digits is 12, while the sum is 9.

The square root of 126 is about 11.2249721603. The cubic root of 126 is about 5.0132979350.

Adding to 126 its reverse (621), we get a palindrome (747).

It can be divided in two parts, 1 and 26, that added together give a cube (27 = 3^{3}).

The spelling of 126 in words is "one hundred twenty-six", and thus it is an aban number.

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