51191591 has 8 divisors (see below), whose sum is σ = 56308368. Its totient is φ = 46536600.

The previous prime is 51191563. The next prime is 51191593. The reversal of 51191591 is 19519115.

It is not a de Polignac number, because 51191591 - 2²² = 46997287 is a prime.

It is a super-2 number, since 2×51191591² = 5241157978222562, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51191593) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17900 + ... + 20561.

It is an arithmetic number, because the mean of its divisors is an integer number (7038546).

Almost surely, 2^51191591 is an apocalyptic number.

51191591 is a deficient number, since it is larger than the sum of its proper divisors (5116777).

51191591 is an equidigital number, since it uses as much as digits as its factorization.

51191591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38494 (or 38472 counting only the distinct ones).

The product of its digits is 2025, while the sum is 32.

The square root of 51191591 is about 7154.8299071327. The cubic root of 51191591 is about 371.3067768674.

The spelling of 51191591 in words is "fifty-one million, one hundred ninety-one thousand, five hundred ninety-one".