661136077 has 6 divisors (see below), whose sum is σ = 769076718. Its totient is φ = 566688024.

The previous prime is 661136059. The next prime is 661136089. The reversal of 661136077 is 770631166.

It can be written as a sum of positive squares in only one way, i.e., 539121961 + 122014116 = 23219^2 + 11046^2 .

It is a de Polignac number, because none of the positive numbers 2^k-661136077 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 (661136057) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6746238 + ... + 6746335.

It is an arithmetic number, because the mean of its divisors is an integer number (128179453).

Almost surely, 2^661136077 is an apocalyptic number.

It is an amenable number.

661136077 is a deficient number, since it is larger than the sum of its proper divisors (107940641).

661136077 is a wasteful number, since it uses less digits than its factorization.

661136077 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13492587 (or 13492580 counting only the distinct ones).

The product of its (nonzero) digits is 31752, while the sum is 37.

The square root of 661136077 is about 25712.5665191167. The cubic root of 661136077 is about 871.1580460881.

The spelling of 661136077 in words is "six hundred sixty-one million, one hundred thirty-six thousand, seventy-seven".