644671306 has 4 divisors (see below), whose sum is σ = 967006962. Its totient is φ = 322335652.

The previous prime is 644671303. The next prime is 644671309. The reversal of 644671306 is 603176446.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (644671303) and next prime (644671309).

It can be written as a sum of positive squares in only one way, i.e., 473454081 + 171217225 = 21759^2 + 13085^2 .

It is not an unprimeable number, because it can be changed into a prime (644671303) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161167825 + ... + 161167828.

Almost surely, 2^644671306 is an apocalyptic number.

644671306 is a deficient number, since it is larger than the sum of its proper divisors (322335656).

644671306 is a wasteful number, since it uses less digits than its factorization.

644671306 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 322335655.

The product of its (nonzero) digits is 72576, while the sum is 37.

The square root of 644671306 is about 25390.3782169545. The cubic root of 644671306 is about 863.8654670574.

The spelling of 644671306 in words is "six hundred forty-four million, six hundred seventy-one thousand, three hundred six".