21465521 has 12 divisors (see below), whose sum is σ = 26966016. Its totient is φ = 16725720.

The previous prime is 21465517. The next prime is 21465523. The reversal of 21465521 is 12556412.

It is not a de Polignac number, because 21465521 - 2² = 21465517 is a prime.

It is a hoax number, since the sum of its digits (26) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21465523) 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, 11825 + ... + 13518.

It is an arithmetic number, because the mean of its divisors is an integer number (2247168).

Almost surely, 2^21465521 is an apocalyptic number.

It is an amenable number.

21465521 is a deficient number, since it is larger than the sum of its proper divisors (5500495).

21465521 is a wasteful number, since it uses less digits than its factorization.

21465521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25372 (or 25361 counting only the distinct ones).

The product of its digits is 2400, while the sum is 26.

The square root of 21465521 is about 4633.0897897623. The cubic root of 21465521 is about 277.9161669481.

It can be divided in two parts, 2146 and 5521, that added together give a palindrome (7667).

The spelling of 21465521 in words is "twenty-one million, four hundred sixty-five thousand, five hundred twenty-one".