51815999 has 2 divisors, whose sum is σ = 51816000. Its totient is φ = 51815998.

The previous prime is 51815993. The next prime is 51816019. The reversal of 51815999 is 99951815.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 51815999 - 2¹⁶ = 51750463 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51815993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25907999 + 25908000.

It is an arithmetic number, because the mean of its divisors is an integer number (25908000).

Almost surely, 2^51815999 is an apocalyptic number.

51815999 is a deficient number, since it is larger than the sum of its proper divisors (1).

51815999 is an equidigital number, since it uses as much as digits as its factorization.

51815999 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 145800, while the sum is 47.

The square root of 51815999 is about 7198.3330709269. Note that the first 3 decimals coincide. The cubic root of 51815999 is about 372.8103480913.

The spelling of 51815999 in words is "fifty-one million, eight hundred fifteen thousand, nine hundred ninety-nine".