51861917 has 6 divisors (see below), whose sum is σ = 55092378. Its totient is φ = 48810944.

The previous prime is 51861911. The next prime is 51861919. The reversal of 51861917 is 71916815.

It can be written as a sum of positive squares in 3 ways, for example, as 36409156 + 15452761 = 6034^2 + 3931^2 .

It is not a de Polignac number, because 51861917 - 2⁸ = 51861661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51861911) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 89438 + ... + 90015.

It is an arithmetic number, because the mean of its divisors is an integer number (9182063).

Almost surely, 2^51861917 is an apocalyptic number.

It is an amenable number.

51861917 is a deficient number, since it is larger than the sum of its proper divisors (3230461).

51861917 is a wasteful number, since it uses less digits than its factorization.

51861917 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 179487 (or 179470 counting only the distinct ones).

The product of its digits is 15120, while the sum is 38.

The square root of 51861917 is about 7201.5218530530. The cubic root of 51861917 is about 372.9204405445.

The spelling of 51861917 in words is "fifty-one million, eight hundred sixty-one thousand, nine hundred seventeen".