21640645166 has 8 divisors (see below), whose sum is σ = 37098248880. Its totient is φ = 9274562208.

The previous prime is 21640645157. The next prime is 21640645171. The reversal of 21640645166 is 66154604612.

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 polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 772880171 + ... + 772880198.

It is an arithmetic number, because the mean of its divisors is an integer number (4637281110).

Almost surely, 2^21640645166 is an apocalyptic number.

21640645166 is a deficient number, since it is larger than the sum of its proper divisors (15457603714).

21640645166 is a wasteful number, since it uses less digits than its factorization.

21640645166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1545760378.

The product of its (nonzero) digits is 207360, while the sum is 41.

The spelling of 21640645166 in words is "twenty-one billion, six hundred forty million, six hundred forty-five thousand, one hundred sixty-six".