365891661 has 32 divisors (see below), whose sum is σ = 551591040. Its totient is φ = 242669520.

The previous prime is 365891657. The next prime is 365891677. The reversal of 365891661 is 166198563.

365891661 is a `hidden beast` number, since 3 + 6 + 589 + 1 + 6 + 61 = 666.

It is not a de Polignac number, because 365891661 - 2² = 365891657 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (365891611) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 640506 + ... + 641076.

It is an arithmetic number, because the mean of its divisors is an integer number (17237220).

Almost surely, 2^365891661 is an apocalyptic number.

It is an amenable number.

365891661 is a deficient number, since it is larger than the sum of its proper divisors (185699379).

365891661 is an frugal number, since it uses more digits than its factorization.

365891661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 885 (or 867 counting only the distinct ones).

The product of its digits is 233280, while the sum is 45.

The square root of 365891661 is about 19128.2947750185. The cubic root of 365891661 is about 715.2384234289.

The spelling of 365891661 in words is "three hundred sixty-five million, eight hundred ninety-one thousand, six hundred sixty-one".