661880993701 has 4 divisors (see below), whose sum is σ = 661882633632. Its totient is φ = 661879353772.

The previous prime is 661880993677. The next prime is 661880993713. The reversal of 661880993701 is 107399088166.

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 a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 661880993701 - 2³⁹ = 112125179813 is a prime.

It is a Smith number, since the sum of its digits (58) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661880993731) 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, 256560 + ... + 1178806.

It is an arithmetic number, because the mean of its divisors is an integer number (165470658408).

Almost surely, 2^661880993701 is an apocalyptic number.

It is an amenable number.

661880993701 is a deficient number, since it is larger than the sum of its proper divisors (1639931).

661880993701 is an equidigital number, since it uses as much as digits as its factorization.

661880993701 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1639930.

The product of its (nonzero) digits is 3919104, while the sum is 58.

The spelling of 661880993701 in words is "six hundred sixty-one billion, eight hundred eighty million, nine hundred ninety-three thousand, seven hundred one".