21691644570 has 48 divisors (see below), whose sum is σ = 58217582592. Its totient is φ = 5597843040.

The previous prime is 21691644553. The next prime is 21691644619. The reversal of 21691644570 is 7544619612.

21691644570 is a `hidden beast` number, since 2 + 1 + 69 + 16 + 4 + 4 + 570 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3884602 + ... + 3890181.

It is an arithmetic number, because the mean of its divisors is an integer number (1212866304).

Almost surely, 2^21691644570 is an apocalyptic number.

21691644570 is an abundant number, since it is smaller than the sum of its proper divisors (36525938022).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21691644570 is a wasteful number, since it uses less digits than its factorization.

21691644570 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7774827 (or 7774824 counting only the distinct ones).

The product of its (nonzero) digits is 362880, while the sum is 45.

The spelling of 21691644570 in words is "twenty-one billion, six hundred ninety-one million, six hundred forty-four thousand, five hundred seventy".