644863877 has 8 divisors (see below), whose sum is σ = 737154816. Its totient is φ = 552614832.

The previous prime is 644863871. The next prime is 644863913. The reversal of 644863877 is 778368446.

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

It is not a de Polignac number, because 644863877 - 2¹⁴ = 644847493 is a prime.

It is a super-2 number, since 2×644863877² = 831698839718942258, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644863871) 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, 36683 + ... + 51335.

It is an arithmetic number, because the mean of its divisors is an integer number (92144352).

Almost surely, 2^644863877 is an apocalyptic number.

It is an amenable number.

644863877 is a deficient number, since it is larger than the sum of its proper divisors (92290939).

644863877 is a wasteful number, since it uses less digits than its factorization.

644863877 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20947.

The product of its digits is 5419008, while the sum is 53.

The square root of 644863877 is about 25394.1701380455. The cubic root of 644863877 is about 863.9514741301.

The spelling of 644863877 in words is "six hundred forty-four million, eight hundred sixty-three thousand, eight hundred seventy-seven".