51781568881 has 4 divisors (see below), whose sum is σ = 59178935872. Its totient is φ = 44384201892.

The previous prime is 51781568873. The next prime is 51781568887. The reversal of 51781568881 is 18886518715.

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 51781568881 - 2³ = 51781568873 is a prime.

It is a super-2 number, since 2×51781568881² (a number of 22 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (51781568887) 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, 3698683485 + ... + 3698683498.

It is an arithmetic number, because the mean of its divisors is an integer number (14794733968).

Almost surely, 2^51781568881 is an apocalyptic number.

It is an amenable number.

51781568881 is a deficient number, since it is larger than the sum of its proper divisors (7397366991).

51781568881 is an equidigital number, since it uses as much as digits as its factorization.

51781568881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7397366990.

The product of its digits is 4300800, while the sum is 58.

The spelling of 51781568881 in words is "fifty-one billion, seven hundred eighty-one million, five hundred sixty-eight thousand, eight hundred eighty-one".