21652491 has 16 divisors (see below), whose sum is σ = 33064704. Its totient is φ = 12346464.

The previous prime is 21652489. The next prime is 21652493. The reversal of 21652491 is 19425612.

It is an interprime number because it is at equal distance from previous prime (21652489) and next prime (21652493).

It is not a de Polignac number, because 21652491 - 2¹ = 21652489 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21652493) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13456 + ... + 14978.

It is an arithmetic number, because the mean of its divisors is an integer number (2066544).

Almost surely, 2^21652491 is an apocalyptic number.

21652491 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21652491 is a deficient number, since it is larger than the sum of its proper divisors (11412213).

21652491 is a wasteful number, since it uses less digits than its factorization.

21652491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2210.

The product of its digits is 4320, while the sum is 30.

The square root of 21652491 is about 4653.2237212496. The cubic root of 21652491 is about 278.7207416320.

It can be divided in two parts, 2165 and 2491, that added together give a triangular number (4656 = T₉₆).

The spelling of 21652491 in words is "twenty-one million, six hundred fifty-two thousand, four hundred ninety-one".