21552531 has 32 divisors (see below), whose sum is σ = 38588928. Its totient is φ = 10333440.

The previous prime is 21552529. The next prime is 21552551. The reversal of 21552531 is 13525512.

It is a happy number.

It is not a de Polignac number, because 21552531 - 2¹ = 21552529 is a prime.

It is a super-2 number, since 2×21552531² = 929023185011922, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21552521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 586 + ... + 6591.

It is an arithmetic number, because the mean of its divisors is an integer number (1205904).

Almost surely, 2^21552531 is an apocalyptic number.

21552531 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21552531 is a deficient number, since it is larger than the sum of its proper divisors (17036397).

21552531 is a wasteful number, since it uses less digits than its factorization.

21552531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7211.

The product of its digits is 1500, while the sum is 24.

The square root of 21552531 is about 4642.4703553173. The cubic root of 21552531 is about 278.2911696642.

The spelling of 21552531 in words is "twenty-one million, five hundred fifty-two thousand, five hundred thirty-one".