21155372 has 24 divisors (see below), whose sum is σ = 42825216. Its totient is φ = 8956368.

The previous prime is 21155371. The next prime is 21155399. The reversal of 21155372 is 27355112.

It is not an unprimeable number, because it can be changed into a prime (21155371) by changing a digit.

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, 2228 + ... + 6875.

It is an arithmetic number, because the mean of its divisors is an integer number (1784384).

Almost surely, 2^21155372 is an apocalyptic number.

It is an amenable number.

21155372 is an abundant number, since it is smaller than the sum of its proper divisors (21669844).

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

21155372 is a wasteful number, since it uses less digits than its factorization.

21155372 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9197 (or 9195 counting only the distinct ones).

The product of its digits is 2100, while the sum is 26.

The square root of 21155372 is about 4599.4969290130. The cubic root of 21155372 is about 276.5711584658.

The spelling of 21155372 in words is "twenty-one million, one hundred fifty-five thousand, three hundred seventy-two".