644774457 has 4 divisors (see below), whose sum is σ = 859699280. Its totient is φ = 429849636.

The previous prime is 644774447. The next prime is 644774467. The reversal of 644774457 is 754477446.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (644774447) and next prime (644774467).

It is not a de Polignac number, because 644774457 - 2⁶ = 644774393 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644774407) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 107462407 + ... + 107462412.

It is an arithmetic number, because the mean of its divisors is an integer number (214924820).

Almost surely, 2^644774457 is an apocalyptic number.

It is an amenable number.

644774457 is a deficient number, since it is larger than the sum of its proper divisors (214924823).

644774457 is a wasteful number, since it uses less digits than its factorization.

644774457 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214924822.

The product of its digits is 2634240, while the sum is 48.

The square root of 644774457 is about 25392.4094366801. The cubic root of 644774457 is about 863.9115390292.

The spelling of 644774457 in words is "six hundred forty-four million, seven hundred seventy-four thousand, four hundred fifty-seven".