644490274 has 4 divisors (see below), whose sum is σ = 966735414. Its totient is φ = 322245136.

The previous prime is 644490257. The next prime is 644490277. The reversal of 644490274 is 472094446.

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

It can be written as a sum of positive squares in only one way, i.e., 624750025 + 19740249 = 24995^2 + 4443^2 .

It is not an unprimeable number, because it can be changed into a prime (644490277) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161122567 + ... + 161122570.

Almost surely, 2^644490274 is an apocalyptic number.

644490274 is a deficient number, since it is larger than the sum of its proper divisors (322245140).

644490274 is a wasteful number, since it uses less digits than its factorization.

644490274 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 322245139.

The product of its (nonzero) digits is 193536, while the sum is 40.

The square root of 644490274 is about 25386.8129941511. The cubic root of 644490274 is about 863.7845979734.

The spelling of 644490274 in words is "six hundred forty-four million, four hundred ninety thousand, two hundred seventy-four".