661696533761 has 4 divisors (see below), whose sum is σ = 661767154224. Its totient is φ = 661625913300.

The previous prime is 661696533739. The next prime is 661696533779. The reversal of 661696533761 is 167335696166.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661696533761 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 661696533761.

It is not an unprimeable number, because it can be changed into a prime (661696533791) 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, 35296175 + ... + 35314916.

It is an arithmetic number, because the mean of its divisors is an integer number (165441788556).

Almost surely, 2^661696533761 is an apocalyptic number.

It is an amenable number.

661696533761 is a deficient number, since it is larger than the sum of its proper divisors (70620463).

661696533761 is an equidigital number, since it uses as much as digits as its factorization.

661696533761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70620462.

The product of its digits is 22044960, while the sum is 59.

The spelling of 661696533761 in words is "six hundred sixty-one billion, six hundred ninety-six million, five hundred thirty-three thousand, seven hundred sixty-one".