644402722 has 4 divisors (see below), whose sum is σ = 966604086. Its totient is φ = 322201360.

The previous prime is 644402713. The next prime is 644402743. The reversal of 644402722 is 227204446.

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., 388050601 + 256352121 = 19699^2 + 16011^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161100679 + ... + 161100682.

Almost surely, 2^644402722 is an apocalyptic number.

644402722 is a deficient number, since it is larger than the sum of its proper divisors (322201364).

644402722 is a wasteful number, since it uses less digits than its factorization.

644402722 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 322201363.

The product of its (nonzero) digits is 21504, while the sum is 31.

The square root of 644402722 is about 25385.0885757761. The cubic root of 644402722 is about 863.7454820514.

The spelling of 644402722 in words is "six hundred forty-four million, four hundred two thousand, seven hundred twenty-two".