51818281 has 4 divisors (see below), whose sum is σ = 52302672. Its totient is φ = 51333892.

The previous prime is 51818251. The next prime is 51818293. The reversal of 51818281 is 18281815.

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, and also an emirpimes, since its reverse is a distinct semiprime: 18281815 = 5 ⋅3656363.

It is not a de Polignac number, because 51818281 - 2²⁵ = 18263849 is a prime.

It is a super-2 number, since 2×51818281² = 5370268491589922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51818201) 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, 242035 + ... + 242248.

It is an arithmetic number, because the mean of its divisors is an integer number (13075668).

Almost surely, 2^51818281 is an apocalyptic number.

It is an amenable number.

51818281 is a deficient number, since it is larger than the sum of its proper divisors (484391).

51818281 is a wasteful number, since it uses less digits than its factorization.

51818281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 484390.

The product of its digits is 5120, while the sum is 34.

The square root of 51818281 is about 7198.4915781016. The cubic root of 51818281 is about 372.8158209230.

The spelling of 51818281 in words is "fifty-one million, eight hundred eighteen thousand, two hundred eighty-one".