665331491 has 4 divisors (see below), whose sum is σ = 725816184. Its totient is φ = 604846800.

The previous prime is 665331481. The next prime is 665331503. The reversal of 665331491 is 194133566.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 665331491 - 2¹⁴ = 665315107 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665331421) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30242330 + ... + 30242351.

It is an arithmetic number, because the mean of its divisors is an integer number (181454046).

Almost surely, 2^665331491 is an apocalyptic number.

665331491 is a deficient number, since it is larger than the sum of its proper divisors (60484693).

665331491 is a wasteful number, since it uses less digits than its factorization.

665331491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60484692.

The product of its digits is 58320, while the sum is 38.

The square root of 665331491 is about 25794.0204504843. The cubic root of 665331491 is about 872.9968832812.

The spelling of 665331491 in words is "six hundred sixty-five million, three hundred thirty-one thousand, four hundred ninety-one".