644018730 has 32 divisors (see below), whose sum is σ = 1554292800. Its totient is φ = 170777472.

The previous prime is 644018719. The next prime is 644018743. The reversal of 644018730 is 37810446.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 644018691 and 644018700.

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, 54595 + ... + 65334.

It is an arithmetic number, because the mean of its divisors is an integer number (48571650).

Almost surely, 2^644018730 is an apocalyptic number.

644018730 is an abundant number, since it is smaller than the sum of its proper divisors (910274070).

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

644018730 is a wasteful number, since it uses less digits than its factorization.

644018730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 120118.

The product of its (nonzero) digits is 16128, while the sum is 33.

The square root of 644018730 is about 25377.5241109136. The cubic root of 644018730 is about 863.5738827056.

The spelling of 644018730 in words is "six hundred forty-four million, eighteen thousand, seven hundred thirty".