645321257 has 8 divisors (see below), whose sum is σ = 749600832. Its totient is φ = 544064400.

The previous prime is 645321247. The next prime is 645321293. The reversal of 645321257 is 752123546.

645321257 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 645321257 - 2²⁴ = 628544041 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645321247) 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, 755219 + ... + 756072.

It is an arithmetic number, because the mean of its divisors is an integer number (93700104).

Almost surely, 2^645321257 is an apocalyptic number.

It is an amenable number.

645321257 is a deficient number, since it is larger than the sum of its proper divisors (104279575).

645321257 is a wasteful number, since it uses less digits than its factorization.

645321257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1511359.

The product of its digits is 50400, while the sum is 35.

The square root of 645321257 is about 25403.1741520622. The cubic root of 645321257 is about 864.1556829835.

The spelling of 645321257 in words is "six hundred forty-five million, three hundred twenty-one thousand, two hundred fifty-seven".