645926641921 has 8 divisors (see below), whose sum is σ = 704711512224. Its totient is φ = 587152482720.

The previous prime is 645926641907. The next prime is 645926641961. The reversal of 645926641921 is 129146629546.

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 645926641921 - 2⁷ = 645926641793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645926641961) 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, 2551420 + ... + 2793133.

It is an arithmetic number, because the mean of its divisors is an integer number (88088939028).

Almost surely, 2^645926641921 is an apocalyptic number.

It is an amenable number.

645926641921 is a deficient number, since it is larger than the sum of its proper divisors (58784870303).

645926641921 is a wasteful number, since it uses less digits than its factorization.

645926641921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5355551.

The product of its digits is 5598720, while the sum is 55.

The spelling of 645926641921 in words is "six hundred forty-five billion, nine hundred twenty-six million, six hundred forty-one thousand, nine hundred twenty-one".