51126220391 has 4 divisors (see below), whose sum is σ = 51464804784. Its totient is φ = 50787636000.

The previous prime is 51126220363. The next prime is 51126220403. The reversal of 51126220391 is 19302262115.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51126220391 is a prime.

It is a super-2 number, since 2×51126220391² (a number of 22 digits) 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 (51126220591) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 169291970 + ... + 169292271.

It is an arithmetic number, because the mean of its divisors is an integer number (12866201196).

Almost surely, 2^51126220391 is an apocalyptic number.

51126220391 is a deficient number, since it is larger than the sum of its proper divisors (338584393).

51126220391 is a wasteful number, since it uses less digits than its factorization.

51126220391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 338584392.

The product of its (nonzero) digits is 6480, while the sum is 32.

The spelling of 51126220391 in words is "fifty-one billion, one hundred twenty-six million, two hundred twenty thousand, three hundred ninety-one".