21160837665 has 24 divisors (see below), whose sum is σ = 40013221248. Its totient is φ = 10259799840.

The previous prime is 21160837651. The next prime is 21160837667. The reversal of 21160837665 is 56673806112.

21160837665 is a `hidden beast` number, since 2 + 1 + 1 + 608 + 37 + 6 + 6 + 5 = 666.

It is not a de Polignac number, because 21160837665 - 2¹¹ = 21160835617 is a prime.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21160837665.

It is not an unprimeable number, because it can be changed into a prime (21160837667) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 21374089 + ... + 21375078.

It is an arithmetic number, because the mean of its divisors is an integer number (1667217552).

Almost surely, 2^21160837665 is an apocalyptic number.

It is an amenable number.

21160837665 is a deficient number, since it is larger than the sum of its proper divisors (18852383583).

21160837665 is a wasteful number, since it uses less digits than its factorization.

21160837665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42749189 (or 42749186 counting only the distinct ones).

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

The spelling of 21160837665 in words is "twenty-one billion, one hundred sixty million, eight hundred thirty-seven thousand, six hundred sixty-five".