644221377 has 8 divisors (see below), whose sum is σ = 954402080. Its totient is φ = 429480900.

The previous prime is 644221327. The next prime is 644221439. The reversal of 644221377 is 773122446.

644221377 is a `hidden beast` number, since 64 + 4 + 221 + 377 = 666.

It is not a de Polignac number, because 644221377 - 2²⁴ = 627444161 is a prime.

It is a super-2 number, since 2×644221377² = 830042365167552258, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644221327) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11929999 + ... + 11930052.

It is an arithmetic number, because the mean of its divisors is an integer number (119300260).

Almost surely, 2^644221377 is an apocalyptic number.

It is an amenable number.

644221377 is a deficient number, since it is larger than the sum of its proper divisors (310180703).

644221377 is a wasteful number, since it uses less digits than its factorization.

644221377 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23860060 (or 23860054 counting only the distinct ones).

The product of its digits is 56448, while the sum is 36.

The square root of 644221377 is about 25381.5164440583. The cubic root of 644221377 is about 863.6644506225.

The spelling of 644221377 in words is "six hundred forty-four million, two hundred twenty-one thousand, three hundred seventy-seven".