51861216551 has 4 divisors (see below), whose sum is σ = 51861889704. Its totient is φ = 51860543400.

The previous prime is 51861216541. The next prime is 51861216553. The reversal of 51861216551 is 15561216815.

It is a happy number.

51861216551 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 51861216551 - 2⁶ = 51861216487 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 51861216499 and 51861216508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51861216553) 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, 203465 + ... + 380946.

It is an arithmetic number, because the mean of its divisors is an integer number (12965472426).

Almost surely, 2^51861216551 is an apocalyptic number.

51861216551 is a deficient number, since it is larger than the sum of its proper divisors (673153).

51861216551 is an equidigital number, since it uses as much as digits as its factorization.

51861216551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 673152.

The product of its digits is 72000, while the sum is 41.

The spelling of 51861216551 in words is "fifty-one billion, eight hundred sixty-one million, two hundred sixteen thousand, five hundred fifty-one".