21135920 has 40 divisors (see below), whose sum is σ = 52923696. Its totient is φ = 7803648.

The previous prime is 21135911. The next prime is 21135971. The reversal of 21135920 is 2953112.

It is a tau number, because it is divible by the number of its divisors (40).

It is a super-2 number, since 2×21135920² = 893454228492800, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9122 + ... + 11201.

Almost surely, 2^21135920 is an apocalyptic number.

21135920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21135920 is an abundant number, since it is smaller than the sum of its proper divisors (31787776).

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

21135920 is a wasteful number, since it uses less digits than its factorization.

21135920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20349 (or 20343 counting only the distinct ones).

The product of its (nonzero) digits is 540, while the sum is 23.

The square root of 21135920 is about 4597.3818636263. The cubic root of 21135920 is about 276.4863650003.

The spelling of 21135920 in words is "twenty-one million, one hundred thirty-five thousand, nine hundred twenty".