646756818797 has 4 divisors (see below), whose sum is σ = 667619942016. Its totient is φ = 625893695580.

The previous prime is 646756818791. The next prime is 646756818821. The reversal of 646756818797 is 797818657646.

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: 797818657646 = 2 ⋅398909328823.

It is a cyclic number.

It is not a de Polignac number, because 646756818797 - 2⁴ = 646756818781 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 (646756818791) 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, 10431561563 + ... + 10431561624.

It is an arithmetic number, because the mean of its divisors is an integer number (166904985504).

Almost surely, 2^646756818797 is an apocalyptic number.

It is an amenable number.

646756818797 is a deficient number, since it is larger than the sum of its proper divisors (20863123219).

646756818797 is a wasteful number, since it uses less digits than its factorization.

646756818797 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20863123218.

The product of its digits is 853493760, while the sum is 74.

The spelling of 646756818797 in words is "six hundred forty-six billion, seven hundred fifty-six million, eight hundred eighteen thousand, seven hundred ninety-seven".