51328205781 has 4 divisors (see below), whose sum is σ = 68437607712. Its totient is φ = 34218803852.

The previous prime is 51328205777. The next prime is 51328205813. The reversal of 51328205781 is 18750282315.

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 51328205781 - 2² = 51328205777 is a prime.

It is a super-2 number, since 2×51328205781² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51328205581) 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, 8554700961 + ... + 8554700966.

It is an arithmetic number, because the mean of its divisors is an integer number (17109401928).

Almost surely, 2^51328205781 is an apocalyptic number.

It is an amenable number.

51328205781 is a deficient number, since it is larger than the sum of its proper divisors (17109401931).

51328205781 is a wasteful number, since it uses less digits than its factorization.

51328205781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17109401930.

The product of its (nonzero) digits is 134400, while the sum is 42.

The spelling of 51328205781 in words is "fifty-one billion, three hundred twenty-eight million, two hundred five thousand, seven hundred eighty-one".