644368156 has 6 divisors (see below), whose sum is σ = 1127644280. Its totient is φ = 322184076.

The previous prime is 644368141. The next prime is 644368159. The reversal of 644368156 is 651863446.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644368159) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80546016 + ... + 80546023.

Almost surely, 2^644368156 is an apocalyptic number.

It is an amenable number.

644368156 is a deficient number, since it is larger than the sum of its proper divisors (483276124).

644368156 is a wasteful number, since it uses less digits than its factorization.

644368156 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161092043 (or 161092041 counting only the distinct ones).

The product of its digits is 414720, while the sum is 43.

The square root of 644368156 is about 25384.4077338826. The cubic root of 644368156 is about 863.7300378997.

The spelling of 644368156 in words is "six hundred forty-four million, three hundred sixty-eight thousand, one hundred fifty-six".