51813457921 has 4 divisors (see below), whose sum is σ = 51815203632. Its totient is φ = 51811712212.

The previous prime is 51813457831. The next prime is 51813457967. The reversal of 51813457921 is 12975431815.

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 51813457921 - 2²³ = 51805069313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51813427921) 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, 827551 + ... + 887956.

It is an arithmetic number, because the mean of its divisors is an integer number (12953800908).

Almost surely, 2^51813457921 is an apocalyptic number.

It is an amenable number.

51813457921 is a deficient number, since it is larger than the sum of its proper divisors (1745711).

51813457921 is a wasteful number, since it uses less digits than its factorization.

51813457921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1745710.

The product of its digits is 302400, while the sum is 46.

The spelling of 51813457921 in words is "fifty-one billion, eight hundred thirteen million, four hundred fifty-seven thousand, nine hundred twenty-one".