644349867 has 16 divisors (see below), whose sum is σ = 989601792. Its totient is φ = 365299200.

The previous prime is 644349859. The next prime is 644349877. The reversal of 644349867 is 768943446.

It is not a de Polignac number, because 644349867 - 2³ = 644349859 is a prime.

It is a super-2 number, since 2×644349867² = 830373502205835378, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (644349847) 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, 118134 + ... + 123467.

It is an arithmetic number, because the mean of its divisors is an integer number (61850112).

Almost surely, 2^644349867 is an apocalyptic number.

644349867 is a deficient number, since it is larger than the sum of its proper divisors (345251925).

644349867 is a wasteful number, since it uses less digits than its factorization.

644349867 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 241738.

The product of its digits is 3483648, while the sum is 51.

The square root of 644349867 is about 25384.0474905008. The cubic root of 644349867 is about 863.7218661178.

The spelling of 644349867 in words is "six hundred forty-four million, three hundred forty-nine thousand, eight hundred sixty-seven".