51915591 has 24 divisors (see below), whose sum is σ = 92295840. Its totient is φ = 27383616.

The previous prime is 51915571. The next prime is 51915641. The reversal of 51915591 is 19551915.

51915591 = 196² + 197² + ... + 546².

51915591 is a `hidden beast` number, since 51 + 9 + 15 + 591 = 666.

It is not a de Polignac number, because 51915591 - 2⁵ = 51915559 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51915511) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 30876 + ... + 32513.

It is an arithmetic number, because the mean of its divisors is an integer number (3845660).

Almost surely, 2^51915591 is an apocalyptic number.

51915591 is a deficient number, since it is larger than the sum of its proper divisors (40380249).

51915591 is a wasteful number, since it uses less digits than its factorization.

51915591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63415 (or 63412 counting only the distinct ones).

The product of its digits is 10125, while the sum is 36.

The square root of 51915591 is about 7205.2474627871. The cubic root of 51915591 is about 373.0490463481.

It can be divided in two parts, 519 and 15591, that added together give a triangular number (16110 = T₁₇₉).

The spelling of 51915591 in words is "fifty-one million, nine hundred fifteen thousand, five hundred ninety-one".