21623657 has 8 divisors (see below), whose sum is σ = 24615360. Its totient is φ = 18802960.

The previous prime is 21623639. The next prime is 21623663. The reversal of 21623657 is 75632612.

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

It is not a de Polignac number, because 21623657 - 2⁶ = 21623593 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21623617) 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, 42482 + ... + 42987.

It is an arithmetic number, because the mean of its divisors is an integer number (3076920).

Almost surely, 2^21623657 is an apocalyptic number.

It is an amenable number.

21623657 is a deficient number, since it is larger than the sum of its proper divisors (2991703).

21623657 is a wasteful number, since it uses less digits than its factorization.

21623657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85503.

The product of its digits is 15120, while the sum is 32.

The square root of 21623657 is about 4650.1244069379. The cubic root of 21623657 is about 278.5969652054.

The spelling of 21623657 in words is "twenty-one million, six hundred twenty-three thousand, six hundred fifty-seven".