661899985231 has 2 divisors, whose sum is σ = 661899985232. Its totient is φ = 661899985230.

The previous prime is 661899985177. The next prime is 661899985319. The reversal of 661899985231 is 132589998166.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 661899985231 - 2¹¹ = 661899983183 is a prime.

It is a super-2 number, since 2×661899985231² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (667899985231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330949992615 + 330949992616.

It is an arithmetic number, because the mean of its divisors is an integer number (330949992616).

Almost surely, 2^661899985231 is an apocalyptic number.

661899985231 is a deficient number, since it is larger than the sum of its proper divisors (1).

661899985231 is an equidigital number, since it uses as much as digits as its factorization.

661899985231 is an evil number, because the sum of its binary digits is even.

The product of its digits is 50388480, while the sum is 67.

The spelling of 661899985231 in words is "six hundred sixty-one billion, eight hundred ninety-nine million, nine hundred eighty-five thousand, two hundred thirty-one".