21664877 has 8 divisors (see below), whose sum is σ = 24084480. Its totient is φ = 19352880.

The previous prime is 21664861. The next prime is 21664879. The reversal of 21664877 is 77846612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21664877 - 2⁴ = 21664861 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21664879) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26477 + ... + 27282.

It is an arithmetic number, because the mean of its divisors is an integer number (3010560).

Almost surely, 2^21664877 is an apocalyptic number.

It is an amenable number.

21664877 is a deficient number, since it is larger than the sum of its proper divisors (2419603).

21664877 is a wasteful number, since it uses less digits than its factorization.

21664877 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53803.

The product of its digits is 112896, while the sum is 41.

The square root of 21664877 is about 4654.5544362484. The cubic root of 21664877 is about 278.7738775822.

The spelling of 21664877 in words is "twenty-one million, six hundred sixty-four thousand, eight hundred seventy-seven".