5121991565 has 8 divisors (see below), whose sum is σ = 6156355320. Its totient is φ = 4090949632.

The previous prime is 5121991559. The next prime is 5121991573. The reversal of 5121991565 is 5651991215.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 161747524 + 4960244041 = 12718^2 + 70429^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 5121991565 - 2⁸ = 5121991309 is a prime.

It is a super-2 number, since 2×5121991565² = 52469595183862298450, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 827060 + ... + 833229.

It is an arithmetic number, because the mean of its divisors is an integer number (769544415).

Almost surely, 2^5121991565 is an apocalyptic number.

It is an amenable number.

5121991565 is a deficient number, since it is larger than the sum of its proper divisors (1034363755).

5121991565 is a wasteful number, since it uses less digits than its factorization.

5121991565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1660911.

The product of its digits is 121500, while the sum is 44.

The square root of 5121991565 is about 71568.0904104616. The cubic root of 5121991565 is about 1723.7711968440.

The spelling of 5121991565 in words is "five billion, one hundred twenty-one million, nine hundred ninety-one thousand, five hundred sixty-five".