644262426 has 24 divisors (see below), whose sum is σ = 1433630484. Its totient is φ = 208949760.

The previous prime is 644262403. The next prime is 644262439. The reversal of 644262426 is 624262446.

644262426 is a `hidden beast` number, since 6 + 4 + 4 + 2 + 624 + 26 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 640039401 + 4223025 = 25299^2 + 2055^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 483015 + ... + 484346.

Almost surely, 2^644262426 is an apocalyptic number.

644262426 is an abundant number, since it is smaller than the sum of its proper divisors (789368058).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644262426 is a wasteful number, since it uses less digits than its factorization.

644262426 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 967406 (or 967403 counting only the distinct ones).

The product of its digits is 110592, while the sum is 36.

The square root of 644262426 is about 25382.3250708047. The cubic root of 644262426 is about 863.6827941145.

The spelling of 644262426 in words is "six hundred forty-four million, two hundred sixty-two thousand, four hundred twenty-six".