644157262433 has 4 divisors (see below), whose sum is σ = 653771550000. Its totient is φ = 634542974868.

The previous prime is 644157262379. The next prime is 644157262451. The reversal of 644157262433 is 334262751446.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 644157262433 - 2¹⁴ = 644157246049 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (644157262453) 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, 4807143683 + ... + 4807143816.

It is an arithmetic number, because the mean of its divisors is an integer number (163442887500).

Almost surely, 2^644157262433 is an apocalyptic number.

It is an amenable number.

644157262433 is a deficient number, since it is larger than the sum of its proper divisors (9614287567).

644157262433 is an equidigital number, since it uses as much as digits as its factorization.

644157262433 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9614287566.

The product of its digits is 2903040, while the sum is 47.

The spelling of 644157262433 in words is "six hundred forty-four billion, one hundred fifty-seven million, two hundred sixty-two thousand, four hundred thirty-three".