64572817681 has 4 divisors (see below), whose sum is σ = 65390195200. Its totient is φ = 63755440164.

The previous prime is 64572817651. The next prime is 64572817691. The reversal of 64572817681 is 18671827546.

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 64572817681 - 2¹³ = 64572809489 is a prime.

It is a super-2 number, since 2×64572817681² (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 (64572817601) 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, 408688641 + ... + 408688798.

It is an arithmetic number, because the mean of its divisors is an integer number (16347548800).

Almost surely, 2^64572817681 is an apocalyptic number.

It is an amenable number.

64572817681 is a deficient number, since it is larger than the sum of its proper divisors (817377519).

64572817681 is an equidigital number, since it uses as much as digits as its factorization.

64572817681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 817377518.

The product of its digits is 4515840, while the sum is 55.

The spelling of 64572817681 in words is "sixty-four billion, five hundred seventy-two million, eight hundred seventeen thousand, six hundred eighty-one".