644023625 has 16 divisors (see below), whose sum is σ = 918562944. Its totient is φ = 441615600.

The previous prime is 644023559. The next prime is 644023637. The reversal of 644023625 is 526320446.

It is not a de Polignac number, because 644023625 - 2¹² = 644019529 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 644023591 and 644023600.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 367139 + ... + 368888.

It is an arithmetic number, because the mean of its divisors is an integer number (57410184).

Almost surely, 2^644023625 is an apocalyptic number.

It is an amenable number.

644023625 is a deficient number, since it is larger than the sum of its proper divisors (274539319).

644023625 is an equidigital number, since it uses as much as digits as its factorization.

644023625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 736049 (or 736039 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 32.

The square root of 644023625 is about 25377.6205543388. The cubic root of 644023625 is about 863.5760706251.

The spelling of 644023625 in words is "six hundred forty-four million, twenty-three thousand, six hundred twenty-five".