51135965821 has 4 divisors (see below), whose sum is σ = 51137568000. Its totient is φ = 51134363644.

The previous prime is 51135965819. The next prime is 51135965891. The reversal of 51135965821 is 12856953115.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 51135965821 - 2¹ = 51135965819 is a prime.

It is a super-2 number, since 2×51135965821² (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 (51135965891) 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, 752221 + ... + 817378.

It is an arithmetic number, because the mean of its divisors is an integer number (12784392000).

Almost surely, 2^51135965821 is an apocalyptic number.

It is an amenable number.

51135965821 is a deficient number, since it is larger than the sum of its proper divisors (1602179).

51135965821 is a wasteful number, since it uses less digits than its factorization.

51135965821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1602178.

The product of its digits is 324000, while the sum is 46.

The spelling of 51135965821 in words is "fifty-one billion, one hundred thirty-five million, nine hundred sixty-five thousand, eight hundred twenty-one".