21605162640738 has 16 divisors (see below), whose sum is σ = 43363011946656. Its totient is φ = 7176273102720.

The previous prime is 21605162640727. The next prime is 21605162640739. The reversal of 21605162640738 is 83704626150612.

It is not an unprimeable number, because it can be changed into a prime (21605162640739) 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, 6361942543 + ... + 6361945938.

It is an arithmetic number, because the mean of its divisors is an integer number (2710188246666).

Almost surely, 2^{21605162640738} is an apocalyptic number.

21605162640738 is an abundant number, since it is smaller than the sum of its proper divisors (21757849305918).

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

21605162640738 is a wasteful number, since it uses less digits than its factorization.

21605162640738 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12723888769.

The product of its (nonzero) digits is 2903040, while the sum is 51.

The spelling of 21605162640738 in words is "twenty-one trillion, six hundred five billion, one hundred sixty-two million, six hundred forty thousand, seven hundred thirty-eight".