1991815265 has 32 divisors (see below), whose sum is σ = 2770364160. Its totient is φ = 1360800000.

The previous prime is 1991815253. The next prime is 1991815289. The reversal of 1991815265 is 5625181991.

It is a happy number.

It is not a de Polignac number, because 1991815265 - 2⁸ = 1991815009 is a prime.

It is a Smith number, since the sum of its digits (47) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 42140 + ... + 75890.

It is an arithmetic number, because the mean of its divisors is an integer number (86573880).

Almost surely, 2^1991815265 is an apocalyptic number.

It is an amenable number.

1991815265 is a deficient number, since it is larger than the sum of its proper divisors (778548895).

1991815265 is a wasteful number, since it uses less digits than its factorization.

1991815265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33833.

The product of its digits is 194400, while the sum is 47.

The square root of 1991815265 is about 44629.7576175359. The cubic root of 1991815265 is about 1258.2000133985.

The spelling of 1991815265 in words is "one billion, nine hundred ninety-one million, eight hundred fifteen thousand, two hundred sixty-five".