644775785467 has 4 divisors (see below), whose sum is σ = 703391765976. Its totient is φ = 586159804960.

The previous prime is 644775785447. The next prime is 644775785473. The reversal of 644775785467 is 764587577446.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644775785467 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 644775785396 and 644775785405.

It is not an unprimeable number, because it can be changed into a prime (644775785447) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 29307990238 + ... + 29307990259.

It is an arithmetic number, because the mean of its divisors is an integer number (175847941494).

Almost surely, 2^644775785467 is an apocalyptic number.

644775785467 is a deficient number, since it is larger than the sum of its proper divisors (58615980509).

644775785467 is a wasteful number, since it uses less digits than its factorization.

644775785467 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58615980508.

The product of its digits is 1106380800, while the sum is 70.

The spelling of 644775785467 in words is "six hundred forty-four billion, seven hundred seventy-five million, seven hundred eighty-five thousand, four hundred sixty-seven".