51978891887 has 4 divisors (see below), whose sum is σ = 55977268200. Its totient is φ = 47980515576.

The previous prime is 51978891863. The next prime is 51978891889. The reversal of 51978891887 is 78819887915.

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

It is a cyclic number.

It is not a de Polignac number, because 51978891887 - 2¹⁴ = 51978875503 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 51978891887.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51978891889) 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, 1999188137 + ... + 1999188162.

It is an arithmetic number, because the mean of its divisors is an integer number (13994317050).

Almost surely, 2^51978891887 is an apocalyptic number.

51978891887 is a deficient number, since it is larger than the sum of its proper divisors (3998376313).

51978891887 is a wasteful number, since it uses less digits than its factorization.

51978891887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3998376312.

The product of its digits is 81285120, while the sum is 71.

The spelling of 51978891887 in words is "fifty-one billion, nine hundred seventy-eight million, eight hundred ninety-one thousand, eight hundred eighty-seven".