661504647877 has 4 divisors (see below), whose sum is σ = 668937284460. Its totient is φ = 654072011296.

The previous prime is 661504647857. The next prime is 661504647913. The reversal of 661504647877 is 778746405166.

661504647877 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 54778934401 + 606725713476 = 234049^2 + 778926^2 .

It is a cyclic number.

It is not a de Polignac number, because 661504647877 - 2²³ = 661496259269 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 (661504647857) 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, 3716318158 + ... + 3716318335.

It is an arithmetic number, because the mean of its divisors is an integer number (167234321115).

Almost surely, 2^661504647877 is an apocalyptic number.

It is an amenable number.

661504647877 is a deficient number, since it is larger than the sum of its proper divisors (7432636583).

661504647877 is an equidigital number, since it uses as much as digits as its factorization.

661504647877 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7432636582.

The product of its (nonzero) digits is 47416320, while the sum is 61.

The spelling of 661504647877 in words is "six hundred sixty-one billion, five hundred four million, six hundred forty-seven thousand, eight hundred seventy-seven".