645715254637 has 4 divisors (see below), whose sum is σ = 649581813216. Its totient is φ = 641848696060.

The previous prime is 645715254577. The next prime is 645715254683. The reversal of 645715254637 is 736452517546.

It is a happy number.

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, and also an emirpimes, since its reverse is a distinct semiprime: 736452517546 = 2 ⋅368226258773.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645715254637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645715284637) 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, 1933279039 + ... + 1933279372.

It is an arithmetic number, because the mean of its divisors is an integer number (162395453304).

Almost surely, 2^645715254637 is an apocalyptic number.

It is an amenable number.

645715254637 is a deficient number, since it is larger than the sum of its proper divisors (3866558579).

645715254637 is a wasteful number, since it uses less digits than its factorization.

645715254637 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3866558578.

The product of its digits is 21168000, while the sum is 55.

The spelling of 645715254637 in words is "six hundred forty-five billion, seven hundred fifteen million, two hundred fifty-four thousand, six hundred thirty-seven".