51397197391 has 8 divisors (see below), whose sum is σ = 52894720160. Its totient is φ = 49905380448.

The previous prime is 51397197359. The next prime is 51397197433. The reversal of 51397197391 is 19379179315.

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

It is a 5-Lehmer number, since φ(51397197391) divides (51397197391-1)⁵.

It is a cyclic number.

It is not a de Polignac number, because 51397197391 - 2⁵ = 51397197359 is a prime.

It is the 226710-th Hogben number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51397197491) by changing a digit.

It is a nontrivial repunit in base 226709.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1408176 + ... + 1444213.

It is an arithmetic number, because the mean of its divisors is an integer number (6611840020).

Almost surely, 2^51397197391 is an apocalyptic number.

51397197391 is a deficient number, since it is larger than the sum of its proper divisors (1497522769).

51397197391 is a wasteful number, since it uses less digits than its factorization.

51397197391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2852913.

The product of its digits is 1607445, while the sum is 55.

The spelling of 51397197391 in words is "fifty-one billion, three hundred ninety-seven million, one hundred ninety-seven thousand, three hundred ninety-one".