21813552 has 30 divisors (see below), whose sum is σ = 61048052. Its totient is φ = 7271136.

The previous prime is 21813527. The next prime is 21813563. The reversal of 21813552 is 25531812.

It is a happy number.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

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 5 ways as a sum of consecutive naturals, for example, 75598 + ... + 75885.

Almost surely, 2^21813552 is an apocalyptic number.

It is an amenable number.

21813552 is an abundant number, since it is smaller than the sum of its proper divisors (39234500).

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

21813552 is a wasteful number, since it uses less digits than its factorization.

21813552 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151497 (or 151488 counting only the distinct ones).

The product of its digits is 2400, while the sum is 27.

The square root of 21813552 is about 4670.4980462473. The cubic root of 21813552 is about 279.4101187028.

The spelling of 21813552 in words is "twenty-one million, eight hundred thirteen thousand, five hundred fifty-two".