61664507616 has 24 divisors (see below), whose sum is σ = 161869332744. Its totient is φ = 20554835840.

The previous prime is 61664507557. The next prime is 61664507617. The reversal of 61664507616 is 61670546616.

It is a tau number, because it is divible by the number of its divisors (24).

It is a super-2 number, since 2×61664507616² (a number of 22 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (48) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61664507617) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 321169215 + ... + 321169406.

It is an arithmetic number, because the mean of its divisors is an integer number (6744555531).

Almost surely, 2^61664507616 is an apocalyptic number.

It is an amenable number.

61664507616 is an abundant number, since it is smaller than the sum of its proper divisors (100204825128).

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

61664507616 is a wasteful number, since it uses less digits than its factorization.

61664507616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 642338634 (or 642338626 counting only the distinct ones).

The product of its (nonzero) digits is 1088640, while the sum is 48.

The spelling of 61664507616 in words is "sixty-one billion, six hundred sixty-four million, five hundred seven thousand, six hundred sixteen".