644216336 has 10 divisors (see below), whose sum is σ = 1248169182. Its totient is φ = 322108160.

The previous prime is 644216317. The next prime is 644216347. The reversal of 644216336 is 633612446.

It can be written as a sum of positive squares in only one way, i.e., 439153936 + 205062400 = 20956^2 + 14320^2 .

It is a junction number, because it is equal to n+sod(n) for n = 644216296 and 644216305.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20131745 + ... + 20131776.

Almost surely, 2^644216336 is an apocalyptic number.

It is an amenable number.

644216336 is a deficient number, since it is larger than the sum of its proper divisors (603952846).

644216336 is a wasteful number, since it uses less digits than its factorization.

644216336 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40263529 (or 40263523 counting only the distinct ones).

The product of its digits is 62208, while the sum is 35.

The square root of 644216336 is about 25381.4171393167. The cubic root of 644216336 is about 863.6621979063.

The spelling of 644216336 in words is "six hundred forty-four million, two hundred sixteen thousand, three hundred thirty-six".