64687861681 has 8 divisors (see below), whose sum is σ = 68468691200. Its totient is φ = 60944652720.

The previous prime is 64687861663. The next prime is 64687861687. The reversal of 64687861681 is 18616878646.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 64687861681 - 2³⁵ = 30328123313 is a prime.

It is a super-2 number, since 2×64687861681² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (64687861687) 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, 9401601 + ... + 9408478.

It is an arithmetic number, because the mean of its divisors is an integer number (8558586400).

Almost surely, 2^64687861681 is an apocalyptic number.

It is an amenable number.

64687861681 is a deficient number, since it is larger than the sum of its proper divisors (3780829519).

64687861681 is a wasteful number, since it uses less digits than its factorization.

64687861681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18810279.

The product of its digits is 18579456, while the sum is 61.

The spelling of 64687861681 in words is "sixty-four billion, six hundred eighty-seven million, eight hundred sixty-one thousand, six hundred eighty-one".