518120921 has 2 divisors, whose sum is σ = 518120922. Its totient is φ = 518120920.

The previous prime is 518120821. The next prime is 518120959. The reversal of 518120921 is 129021815.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 447745600 + 70375321 = 21160^2 + 8389^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-518120921 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (518120021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 259060460 + 259060461.

It is an arithmetic number, because the mean of its divisors is an integer number (259060461).

Almost surely, 2^518120921 is an apocalyptic number.

It is an amenable number.

518120921 is a deficient number, since it is larger than the sum of its proper divisors (1).

518120921 is an equidigital number, since it uses as much as digits as its factorization.

518120921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1440, while the sum is 29.

The square root of 518120921 is about 22762.2696803285. The cubic root of 518120921 is about 803.1753593781.

The spelling of 518120921 in words is "five hundred eighteen million, one hundred twenty thousand, nine hundred twenty-one".