645431320023 has 16 divisors (see below), whose sum is σ = 983547667200. Its totient is φ = 368805419136.

The previous prime is 645431319979. The next prime is 645431320031. The reversal of 645431320023 is 320023134546.

It is a happy number.

It is not a de Polignac number, because 645431320023 - 2³⁷ = 507992366551 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645431320043) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 134736 + ... + 1144122.

It is an arithmetic number, because the mean of its divisors is an integer number (61471729200).

Almost surely, 2^645431320023 is an apocalyptic number.

645431320023 is a deficient number, since it is larger than the sum of its proper divisors (338116347177).

645431320023 is a wasteful number, since it uses less digits than its factorization.

645431320023 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1039846.

The product of its (nonzero) digits is 51840, while the sum is 33.

Adding to 645431320023 its reverse (320023134546), we get a palindrome (965454454569).

The spelling of 645431320023 in words is "six hundred forty-five billion, four hundred thirty-one million, three hundred twenty thousand, twenty-three".