21012504 has 16 divisors (see below), whose sum is σ = 52531320. Its totient is φ = 7004160.

The previous prime is 21012503. The next prime is 21012517. The reversal of 21012504 is 40521012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012503) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 437737 + ... + 437784.

Almost surely, 2^21012504 is an apocalyptic number.

21012504 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21012504 is an abundant number, since it is smaller than the sum of its proper divisors (31518816).

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

21012504 is a wasteful number, since it uses less digits than its factorization.

21012504 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 875530 (or 875526 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 15.

The square root of 21012504 is about 4583.9397901805. The cubic root of 21012504 is about 275.9471648496.

Adding to 21012504 its reverse (40521012), we get a palindrome (61533516).

The spelling of 21012504 in words is "twenty-one million, twelve thousand, five hundred four".