51191391 has 8 divisors (see below), whose sum is σ = 68288944. Its totient is φ = 34110720.

The previous prime is 51191389. The next prime is 51191419. The reversal of 51191391 is 19319115.

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

It is not a de Polignac number, because 51191391 - 2¹ = 51191389 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 (51191381) 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, 7545 + ... + 12621.

It is an arithmetic number, because the mean of its divisors is an integer number (8536118).

Almost surely, 2^51191391 is an apocalyptic number.

51191391 is a deficient number, since it is larger than the sum of its proper divisors (17097553).

51191391 is a wasteful number, since it uses less digits than its factorization.

51191391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8441.

The product of its digits is 1215, while the sum is 30.

The square root of 51191391 is about 7154.8159305464. The cubic root of 51191391 is about 371.3062933150.

The spelling of 51191391 in words is "fifty-one million, one hundred ninety-one thousand, three hundred ninety-one".