64407637681 has 4 divisors (see below), whose sum is σ = 64516251492. Its totient is φ = 64299023872.

The previous prime is 64407637649. The next prime is 64407637703. The reversal of 64407637681 is 18673670446.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 50814176400 + 13593461281 = 225420^2 + 116591^2 .

It is a cyclic number.

It is not a de Polignac number, because 64407637681 - 2⁵ = 64407637649 is a prime.

It is a super-2 number, since 2×64407637681² (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 (64407637181) 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, 54306016 + ... + 54307201.

It is an arithmetic number, because the mean of its divisors is an integer number (16129062873).

Almost surely, 2^64407637681 is an apocalyptic number.

It is an amenable number.

64407637681 is a deficient number, since it is larger than the sum of its proper divisors (108613811).

64407637681 is a wasteful number, since it uses less digits than its factorization.

64407637681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 108613810.

The product of its (nonzero) digits is 4064256, while the sum is 52.

The spelling of 64407637681 in words is "sixty-four billion, four hundred seven million, six hundred thirty-seven thousand, six hundred eighty-one".