644742698 has 8 divisors (see below), whose sum is σ = 970556580. Its totient is φ = 321223840.

The previous prime is 644742677. The next prime is 644742719. The reversal of 644742698 is 896247446.

It is an interprime number because it is at equal distance from previous prime (644742677) and next prime (644742719).

It can be written as a sum of positive squares in 2 ways, for example, as 618865129 + 25877569 = 24877^2 + 5087^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 573053 + ... + 574176.

Almost surely, 2^644742698 is an apocalyptic number.

644742698 is a deficient number, since it is larger than the sum of its proper divisors (325813882).

644742698 is a wasteful number, since it uses less digits than its factorization.

644742698 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1147512.

The product of its digits is 2322432, while the sum is 50.

The square root of 644742698 is about 25391.7840649293. The cubic root of 644742698 is about 863.8973545255.

The spelling of 644742698 in words is "six hundred forty-four million, seven hundred forty-two thousand, six hundred ninety-eight".