21025424 has 40 divisors (see below), whose sum is σ = 46776768. Its totient is φ = 8968320.

The previous prime is 21025423. The next prime is 21025439. The reversal of 21025424 is 42452012.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21025396 and 21025405.

It is not an unprimeable number, because it can be changed into a prime (21025423) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 38594 + ... + 39134.

Almost surely, 2^21025424 is an apocalyptic number.

It is an amenable number.

21025424 is an abundant number, since it is smaller than the sum of its proper divisors (25751344).

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

21025424 is a wasteful number, since it uses less digits than its factorization.

21025424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 903 (or 897 counting only the distinct ones).

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

The square root of 21025424 is about 4585.3488416913. The cubic root of 21025424 is about 276.0037106551.

Adding to 21025424 its reverse (42452012), we get a palindrome (63477436).

The spelling of 21025424 in words is "twenty-one million, twenty-five thousand, four hundred twenty-four".