51820109 has 4 divisors (see below), whose sum is σ = 56531040. Its totient is φ = 47109180.

The previous prime is 51820099. The next prime is 51820133. The reversal of 51820109 is 90102815.

It is a happy number.

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 51820109 - 2²⁰ = 50771533 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51820159) 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, 2355449 + ... + 2355470.

It is an arithmetic number, because the mean of its divisors is an integer number (14132760).

Almost surely, 2^51820109 is an apocalyptic number.

It is an amenable number.

51820109 is a deficient number, since it is larger than the sum of its proper divisors (4710931).

51820109 is a wasteful number, since it uses less digits than its factorization.

51820109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4710930.

The product of its (nonzero) digits is 720, while the sum is 26.

The square root of 51820109 is about 7198.6185480271. The cubic root of 51820109 is about 372.8202048283.

The spelling of 51820109 in words is "fifty-one million, eight hundred twenty thousand, one hundred nine".