645122623 has 4 divisors (see below), whose sum is σ = 648726840. Its totient is φ = 641518408.

The previous prime is 645122609. The next prime is 645122627. The reversal of 645122623 is 326221546.

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-645122623 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 (645122627) 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, 1801840 + ... + 1802197.

It is an arithmetic number, because the mean of its divisors is an integer number (162181710).

Almost surely, 2^645122623 is an apocalyptic number.

645122623 is a deficient number, since it is larger than the sum of its proper divisors (3604217).

645122623 is a wasteful number, since it uses less digits than its factorization.

645122623 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3604216.

The product of its digits is 17280, while the sum is 31.

The square root of 645122623 is about 25399.2642216266. The cubic root of 645122623 is about 864.0670096740.

The spelling of 645122623 in words is "six hundred forty-five million, one hundred twenty-two thousand, six hundred twenty-three".