21640886 has 8 divisors (see below), whose sum is σ = 34169880. Its totient is φ = 10250928.

The previous prime is 21640877. The next prime is 21640891. The reversal of 21640886 is 68804612.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 284711 + ... + 284786.

It is an arithmetic number, because the mean of its divisors is an integer number (4271235).

Almost surely, 2^21640886 is an apocalyptic number.

21640886 is a deficient number, since it is larger than the sum of its proper divisors (12528994).

21640886 is a wasteful number, since it uses less digits than its factorization.

21640886 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 569518.

The product of its (nonzero) digits is 18432, while the sum is 35.

The square root of 21640886 is about 4651.9765691585. The cubic root of 21640886 is about 278.6709377819.

The spelling of 21640886 in words is "twenty-one million, six hundred forty thousand, eight hundred eighty-six".