661866797 has 16 divisors (see below), whose sum is σ = 731799360. Its totient is φ = 595784448.

The previous prime is 661866787. The next prime is 661866827. The reversal of 661866797 is 797668166.

It is not a de Polignac number, because 661866797 - 2⁴ = 661866781 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 (661866727) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 46478 + ... + 59024.

It is an arithmetic number, because the mean of its divisors is an integer number (45737460).

Almost surely, 2^661866797 is an apocalyptic number.

It is an amenable number.

661866797 is a deficient number, since it is larger than the sum of its proper divisors (69932563).

661866797 is a wasteful number, since it uses less digits than its factorization.

661866797 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12700.

The product of its digits is 4572288, while the sum is 56.

The square root of 661866797 is about 25726.7719895054. The cubic root of 661866797 is about 871.4788767763.

The spelling of 661866797 in words is "six hundred sixty-one million, eight hundred sixty-six thousand, seven hundred ninety-seven".