64145375681 has 4 divisors (see below), whose sum is σ = 67918633092. Its totient is φ = 60372118272.

The previous prime is 64145375659. The next prime is 64145375713. The reversal of 64145375681 is 18657354146.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18657354146 = 2 ⋅9328677073.

It can be written as a sum of positive squares in 2 ways, for example, as 37165670656 + 26979705025 = 192784^2 + 164255^2 .

It is a cyclic number.

It is not a de Polignac number, because 64145375681 - 2¹⁴ = 64145359297 is a prime.

It is a super-2 number, since 2×64145375681² (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 (64145375621) 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, 1886628680 + ... + 1886628713.

It is an arithmetic number, because the mean of its divisors is an integer number (16979658273).

Almost surely, 2^64145375681 is an apocalyptic number.

It is an amenable number.

64145375681 is a deficient number, since it is larger than the sum of its proper divisors (3773257411).

64145375681 is a wasteful number, since it uses less digits than its factorization.

64145375681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3773257410.

The product of its digits is 2419200, while the sum is 50.

The spelling of 64145375681 in words is "sixty-four billion, one hundred forty-five million, three hundred seventy-five thousand, six hundred eighty-one".