21402524 has 96 divisors (see below), whose sum is σ = 48771072. Its totient is φ = 8064000.

The previous prime is 21402523. The next prime is 21402527. The reversal of 21402524 is 42520412.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21402496 and 21402505.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21402523) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 301409 + ... + 301479.

It is an arithmetic number, because the mean of its divisors is an integer number (508032).

Almost surely, 2^21402524 is an apocalyptic number.

It is an amenable number.

21402524 is an abundant number, since it is smaller than the sum of its proper divisors (27368548).

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

21402524 is a wasteful number, since it uses less digits than its factorization.

21402524 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 147 (or 145 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 20.

The square root of 21402524 is about 4626.2861995341. The cubic root of 21402524 is about 277.6440244717.

Adding to 21402524 its reverse (42520412), we get a palindrome (63922936).

It can be divided in two parts, 2140 and 2524, that added together give a palindrome (4664).

The spelling of 21402524 in words is "twenty-one million, four hundred two thousand, five hundred twenty-four".