21251124 has 18 divisors (see below), whose sum is σ = 53718210. Its totient is φ = 7083696.

The previous prime is 21251123. The next prime is 21251129. The reversal of 21251124 is 42115212.

It can be written as a sum of positive squares in only one way, i.e., 17791524 + 3459600 = 4218^2 + 1860^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a super-2 number, since 2×21251124² = 903220542526752, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21251097 and 21251106.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21251123) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 295119 + ... + 295190.

It is an arithmetic number, because the mean of its divisors is an integer number (2984345).

Almost surely, 2^21251124 is an apocalyptic number.

It is an amenable number.

21251124 is an abundant number, since it is smaller than the sum of its proper divisors (32467086).

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

21251124 is a wasteful number, since it uses less digits than its factorization.

21251124 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 590319 (or 590314 counting only the distinct ones).

The product of its digits is 160, while the sum is 18.

The square root of 21251124 is about 4609.8941419516. The cubic root of 21251124 is about 276.9877963405.

Adding to 21251124 its reverse (42115212), we get a palindrome (63366336).

It can be divided in two parts, 2125 and 1124, that added together give a square (3249 = 57²).

The spelling of 21251124 in words is "twenty-one million, two hundred fifty-one thousand, one hundred twenty-four".