644505227 has 4 divisors (see below), whose sum is σ = 654124776. Its totient is φ = 634885680.

The previous prime is 644505181. The next prime is 644505259. The reversal of 644505227 is 722505446.

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

It is a cyclic number.

It is not a de Polignac number, because 644505227 - 2⁶ = 644505163 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644505427) 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, 4809674 + ... + 4809807.

It is an arithmetic number, because the mean of its divisors is an integer number (163531194).

Almost surely, 2^644505227 is an apocalyptic number.

644505227 is a gapful number since it is divisible by the number (67) formed by its first and last digit.

644505227 is a deficient number, since it is larger than the sum of its proper divisors (9619549).

644505227 is an equidigital number, since it uses as much as digits as its factorization.

644505227 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9619548.

The product of its (nonzero) digits is 67200, while the sum is 35.

The square root of 644505227 is about 25387.1074957349. The cubic root of 644505227 is about 863.7912782248.

The spelling of 644505227 in words is "six hundred forty-four million, five hundred five thousand, two hundred twenty-seven".