21621512 has 32 divisors (see below), whose sum is σ = 44435520. Its totient is φ = 9781440.

The previous prime is 21621497. The next prime is 21621527. The reversal of 21621512 is 21512612.

It is an interprime number because it is at equal distance from previous prime (21621497) and next prime (21621527).

It is a super-2 number, since 2×21621512² = 934979562332288, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23933 + ... + 24819.

It is an arithmetic number, because the mean of its divisors is an integer number (1388610).

Almost surely, 2^21621512 is an apocalyptic number.

21621512 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21621512 is an abundant number, since it is smaller than the sum of its proper divisors (22814008).

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

21621512 is a wasteful number, since it uses less digits than its factorization.

21621512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1181 (or 1177 counting only the distinct ones).

The product of its digits is 240, while the sum is 20.

The square root of 21621512 is about 4649.8937622273. The cubic root of 21621512 is about 278.5877529146.

Subtracting from 21621512 its reverse (21512612), we obtain a square (108900 = 330²).

The spelling of 21621512 in words is "twenty-one million, six hundred twenty-one thousand, five hundred twelve".