21532491 has 12 divisors (see below), whose sum is σ = 32739720. Its totient is φ = 13599360.

The previous prime is 21532417. The next prime is 21532499. The reversal of 21532491 is 19423512.

It is not a de Polignac number, because 21532491 - 2¹³ = 21524299 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21532499) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 62790 + ... + 63131.

It is an arithmetic number, because the mean of its divisors is an integer number (2728310).

Almost surely, 2^21532491 is an apocalyptic number.

21532491 is a deficient number, since it is larger than the sum of its proper divisors (11207229).

21532491 is a wasteful number, since it uses less digits than its factorization.

21532491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125946 (or 125943 counting only the distinct ones).

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

The square root of 21532491 is about 4640.3115197150. The cubic root of 21532491 is about 278.2048892415.

The spelling of 21532491 in words is "twenty-one million, five hundred thirty-two thousand, four hundred ninety-one".