65721620660 has 12 divisors (see below), whose sum is σ = 138015403428. Its totient is φ = 26288648256.

The previous prime is 65721620647. The next prime is 65721620717. The reversal of 65721620660 is 6602612756.

It can be written as a sum of positive squares in 2 ways, for example, as 19253782564 + 46467838096 = 138758^2 + 215564^2 .

It is a hoax number, since the sum of its digits (41) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

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 3 ways as a sum of consecutive naturals, for example, 1643040497 + ... + 1643040536.

It is an arithmetic number, because the mean of its divisors is an integer number (11501283619).

Almost surely, 2^65721620660 is an apocalyptic number.

It is an amenable number.

65721620660 is an abundant number, since it is smaller than the sum of its proper divisors (72293782768).

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

65721620660 is a wasteful number, since it uses less digits than its factorization.

65721620660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3286081042 (or 3286081040 counting only the distinct ones).

The product of its (nonzero) digits is 181440, while the sum is 41.

The spelling of 65721620660 in words is "sixty-five billion, seven hundred twenty-one million, six hundred twenty thousand, six hundred sixty".