21540465 has 32 divisors (see below), whose sum is σ = 38486400. Its totient is φ = 11430720.

The previous prime is 21540439. The next prime is 21540473. The reversal of 21540465 is 56404512.

It is not a de Polignac number, because 21540465 - 2⁸ = 21540209 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 50955 + ... + 51375.

It is an arithmetic number, because the mean of its divisors is an integer number (1202700).

Almost surely, 2^21540465 is an apocalyptic number.

It is an amenable number.

21540465 is a deficient number, since it is larger than the sum of its proper divisors (16945935).

21540465 is a wasteful number, since it uses less digits than its factorization.

21540465 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 814 (or 808 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 27.

The square root of 21540465 is about 4641.1706497391. The cubic root of 21540465 is about 278.2392269933.

Adding to 21540465 its reverse (56404512), we get a palindrome (77944977).

The spelling of 21540465 in words is "twenty-one million, five hundred forty thousand, four hundred sixty-five".