51881978809 has 4 divisors (see below), whose sum is σ = 51882770916. Its totient is φ = 51881186704.

The previous prime is 51881978777. The next prime is 51881978843. The reversal of 51881978809 is 90887918815.

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

It can be written as a sum of positive squares in 2 ways, for example, as 15466653225 + 36415325584 = 124365^2 + 190828^2 .

It is a cyclic number.

It is not a de Polignac number, because 51881978809 - 2⁵ = 51881978777 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51881978609) 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, 287974 + ... + 432079.

It is an arithmetic number, because the mean of its divisors is an integer number (12970692729).

Almost surely, 2^51881978809 is an apocalyptic number.

It is an amenable number.

51881978809 is a deficient number, since it is larger than the sum of its proper divisors (792107).

51881978809 is an equidigital number, since it uses as much as digits as its factorization.

51881978809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 792106.

The product of its (nonzero) digits is 11612160, while the sum is 64.

The spelling of 51881978809 in words is "fifty-one billion, eight hundred eighty-one million, nine hundred seventy-eight thousand, eight hundred nine".