646027720645 has 8 divisors (see below), whose sum is σ = 775889692920. Its totient is φ = 516384557760.

The previous prime is 646027720627. The next prime is 646027720649. The reversal of 646027720645 is 546027720646.

It can be written as a sum of positive squares in 4 ways, for example, as 101971010241 + 544056710404 = 319329^2 + 737602^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 646027720645 - 2¹¹ = 646027718597 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646027720649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 54695850 + ... + 54707659.

It is an arithmetic number, because the mean of its divisors is an integer number (96986211615).

Almost surely, 2^646027720645 is an apocalyptic number.

It is an amenable number.

646027720645 is a deficient number, since it is larger than the sum of its proper divisors (129861972275).

646027720645 is a wasteful number, since it uses less digits than its factorization.

646027720645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109404695.

The product of its (nonzero) digits is 3386880, while the sum is 49.

Subtracting from 646027720645 its reverse (546027720646), we obtain a palindrome (99999999999).

The spelling of 646027720645 in words is "six hundred forty-six billion, twenty-seven million, seven hundred twenty thousand, six hundred forty-five".