644774487777 has 24 divisors (see below), whose sum is σ = 1064411563904. Its totient is φ = 368434972224.

The previous prime is 644774487761. The next prime is 644774487787. The reversal of 644774487777 is 777784477446.

644774487777 is a `hidden beast` number, since 6 + 4 + 4 + 7 + 74 + 487 + 7 + 77 = 666.

It is not a de Polignac number, because 644774487777 - 2⁴ = 644774487761 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644774487737) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4701693 + ... + 4836885.

Almost surely, 2^644774487777 is an apocalyptic number.

It is an amenable number.

644774487777 is a deficient number, since it is larger than the sum of its proper divisors (419637076127).

644774487777 is a wasteful number, since it uses less digits than its factorization.

644774487777 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 210909 (or 210906 counting only the distinct ones).

The product of its digits is 1445670912, while the sum is 72.

The spelling of 644774487777 in words is "six hundred forty-four billion, seven hundred seventy-four million, four hundred eighty-seven thousand, seven hundred seventy-seven".