646172878431 has 16 divisors (see below), whose sum is σ = 891904563200. Its totient is φ = 415691192160.

The previous prime is 646172878411. The next prime is 646172878453. The reversal of 646172878431 is 134878271646.

It is not a de Polignac number, because 646172878431 - 2⁵ = 646172878399 is a prime.

It is a super-2 number, since 2×646172878431² (a number of 24 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 (646172878411) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9921835 + ... + 9986748.

It is an arithmetic number, because the mean of its divisors is an integer number (55744035200).

Almost surely, 2^646172878431 is an apocalyptic number.

646172878431 is a deficient number, since it is larger than the sum of its proper divisors (245731684769).

646172878431 is a wasteful number, since it uses less digits than its factorization.

646172878431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19908966.

The product of its digits is 10838016, while the sum is 57.

The spelling of 646172878431 in words is "six hundred forty-six billion, one hundred seventy-two million, eight hundred seventy-eight thousand, four hundred thirty-one".