21121508 has 24 divisors (see below), whose sum is σ = 37806048. Its totient is φ = 10322816.

The previous prime is 21121501. The next prime is 21121511. The reversal of 21121508 is 80512112.

It is a happy number.

It is a super-2 number, since 2×21121508² = 892236200388128, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21121508.

It is not an unprimeable number, because it can be changed into a prime (21121501) 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, 37235 + ... + 37797.

It is an arithmetic number, because the mean of its divisors is an integer number (1575252).

Almost surely, 2^21121508 is an apocalyptic number.

It is an amenable number.

21121508 is a deficient number, since it is larger than the sum of its proper divisors (16684540).

21121508 is a wasteful number, since it uses less digits than its factorization.

21121508 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 763 (or 761 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 20.

The square root of 21121508 is about 4595.8141824926. The cubic root of 21121508 is about 276.4235079064.

The spelling of 21121508 in words is "twenty-one million, one hundred twenty-one thousand, five hundred eight".