644476600849 has 3 divisors (see below), whose sum is σ = 644477403643. Its totient is φ = 644475798056.

The previous prime is 644476600829. The next prime is 644476600909. The reversal of 644476600849 is 948006674446.

The square root of 644476600849 is 802793.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 572420862225 + 72055738624 = 756585^2 + 268432^2 .

It is a de Polignac number, because none of the positive numbers 2^k-644476600849 is a prime.

It is a Smith number, since the sum of its digits (58) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 644476600793 and 644476600802.

It is not an unprimeable number, because it can be changed into a prime (644476600829) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 401397 + ... + 1204189.

Almost surely, 2^644476600849 is an apocalyptic number.

644476600849 is the 802793-rd square number.

644476600849 is the 401397-th centered octagonal number.

It is an amenable number.

644476600849 is a deficient number, since it is larger than the sum of its proper divisors (802794).

644476600849 is an frugal number, since it uses more digits than its factorization.

644476600849 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1605586 (or 802793 counting only the distinct ones).

The product of its (nonzero) digits is 27869184, while the sum is 58.

The spelling of 644476600849 in words is "six hundred forty-four billion, four hundred seventy-six million, six hundred thousand, eight hundred forty-nine".