65642689621 has 4 divisors (see below), whose sum is σ = 65698747744. Its totient is φ = 65586631500.

The previous prime is 65642689613. The next prime is 65642689681. The reversal of 65642689621 is 12698624656.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 65642689621 - 2³ = 65642689613 is a prime.

It is a super-2 number, since 2×65642689621² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65642689681) 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, 28027305 + ... + 28029646.

It is an arithmetic number, because the mean of its divisors is an integer number (16424686936).

Almost surely, 2^65642689621 is an apocalyptic number.

It is an amenable number.

65642689621 is a deficient number, since it is larger than the sum of its proper divisors (56058123).

65642689621 is a wasteful number, since it uses less digits than its factorization.

65642689621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56058122.

The product of its digits is 7464960, while the sum is 55.

The spelling of 65642689621 in words is "sixty-five billion, six hundred forty-two million, six hundred eighty-nine thousand, six hundred twenty-one".