391193661 has 16 divisors (see below), whose sum is σ = 534364160. Its totient is φ = 254424240.

The previous prime is 391193653. The next prime is 391193687. The reversal of 391193661 is 166391193.

It is not a de Polignac number, because 391193661 - 2³ = 391193653 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 (391193651) 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, 163806 + ... + 166176.

It is an arithmetic number, because the mean of its divisors is an integer number (33397760).

Almost surely, 2^391193661 is an apocalyptic number.

It is an amenable number.

391193661 is a deficient number, since it is larger than the sum of its proper divisors (143170499).

391193661 is a wasteful number, since it uses less digits than its factorization.

391193661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3696.

The product of its digits is 26244, while the sum is 39.

The square root of 391193661 is about 19778.6162559467. The cubic root of 391193661 is about 731.3589878608.

The spelling of 391193661 in words is "three hundred ninety-one million, one hundred ninety-three thousand, six hundred sixty-one".