51981817 has 8 divisors (see below), whose sum is σ = 55266624. Its totient is φ = 48782448.

The previous prime is 51981803. The next prime is 51981827. The reversal of 51981817 is 71818915.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-51981817 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 51981817.

It is not an unprimeable number, because it can be changed into a prime (51981827) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20103 + ... + 22540.

It is an arithmetic number, because the mean of its divisors is an integer number (6908328).

Almost surely, 2^51981817 is an apocalyptic number.

It is an amenable number.

51981817 is a deficient number, since it is larger than the sum of its proper divisors (3284807).

51981817 is a wasteful number, since it uses less digits than its factorization.

51981817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42719.

The product of its digits is 20160, while the sum is 40.

The square root of 51981817 is about 7209.8416764864. The cubic root of 51981817 is about 373.2076053212.

The spelling of 51981817 in words is "fifty-one million, nine hundred eighty-one thousand, eight hundred seventeen".