661724836791 has 32 divisors (see below), whose sum is σ = 937156608000. Its totient is φ = 414144073728.

The previous prime is 661724836777. The next prime is 661724836807. The reversal of 661724836791 is 197638427166.

It is not a de Polignac number, because 661724836791 - 2⁶ = 661724836727 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661724835791) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 43076170 + ... + 43091528.

It is an arithmetic number, because the mean of its divisors is an integer number (29286144000).

Almost surely, 2^661724836791 is an apocalyptic number.

661724836791 is a deficient number, since it is larger than the sum of its proper divisors (275431771209).

661724836791 is a wasteful number, since it uses less digits than its factorization.

661724836791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22183.

The product of its digits is 18289152, while the sum is 60.

The spelling of 661724836791 in words is "six hundred sixty-one billion, seven hundred twenty-four million, eight hundred thirty-six thousand, seven hundred ninety-one".