991733661 has 12 divisors (see below), whose sum is σ = 1433147040. Its totient is φ = 660859080.

The previous prime is 991733651. The next prime is 991733683. The reversal of 991733661 is 166337199.

It is not a de Polignac number, because 991733661 - 2⁵ = 991733629 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991733621) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2505 + ... + 44606.

It is an arithmetic number, because the mean of its divisors is an integer number (119428920).

Almost surely, 2^991733661 is an apocalyptic number.

It is an amenable number.

991733661 is a deficient number, since it is larger than the sum of its proper divisors (441413379).

991733661 is a wasteful number, since it uses less digits than its factorization.

991733661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49456 (or 49453 counting only the distinct ones).

The product of its digits is 183708, while the sum is 45.

The square root of 991733661 is about 31491.8030763562. The cubic root of 991733661 is about 997.2369261210.

The spelling of 991733661 in words is "nine hundred ninety-one million, seven hundred thirty-three thousand, six hundred sixty-one".