21906252 has 36 divisors (see below), whose sum is σ = 57286320. Its totient is φ = 7049952.

The previous prime is 21906233. The next prime is 21906263. The reversal of 21906252 is 25260912.

It is a tau number, because it is divible by the number of its divisors (36).

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 11 ways as a sum of consecutive naturals, for example, 9448 + ... + 11535.

Almost surely, 2^21906252 is an apocalyptic number.

It is an amenable number.

21906252 is an abundant number, since it is smaller than the sum of its proper divisors (35380068).

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

21906252 is a wasteful number, since it uses less digits than its factorization.

21906252 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21022 (or 21017 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 21906252 is about 4680.4115203687. The cubic root of 21906252 is about 279.8053579231.

The spelling of 21906252 in words is "twenty-one million, nine hundred six thousand, two hundred fifty-two".