123642640 has 120 divisors (see below), whose sum is σ = 323276184. Its totient is φ = 43929600.

The previous prime is 123642619. The next prime is 123642643. The reversal of 123642640 is 46246321.

123642640 is nontrivially palindromic in base 15.

It can be written as a sum of positive squares in 4 ways, for example, as 35808256 + 87834384 = 5984^2 + 9372^2 .

It is a junction number, because it is equal to n+sod(n) for n = 123642599 and 123642608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (123642643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 512920 + ... + 513160.

Almost surely, 2^123642640 is an apocalyptic number.

123642640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 123642640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (161638092).

123642640 is an abundant number, since it is smaller than the sum of its proper divisors (199633544).

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

123642640 is a wasteful number, since it uses less digits than its factorization.

123642640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 329 (or 312 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 28.

The square root of 123642640 is about 11119.4712104488. The cubic root of 123642640 is about 498.1835960103.

Adding to 123642640 its reverse (46246321), we get a palindrome (169888961).

The spelling of 123642640 in words is "one hundred twenty-three million, six hundred forty-two thousand, six hundred forty".