511555991 has 2 divisors, whose sum is σ = 511555992. Its totient is φ = 511555990.

The previous prime is 511555939. The next prime is 511555997. The reversal of 511555991 is 199555115.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 511555991 - 2¹⁴ = 511539607 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (511555997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 255777995 + 255777996.

It is an arithmetic number, because the mean of its divisors is an integer number (255777996).

Almost surely, 2^511555991 is an apocalyptic number.

511555991 is a deficient number, since it is larger than the sum of its proper divisors (1).

511555991 is an equidigital number, since it uses as much as digits as its factorization.

511555991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 50625, while the sum is 41.

The square root of 511555991 is about 22617.6035644805. The cubic root of 511555991 is about 799.7686784319.

The spelling of 511555991 in words is "five hundred eleven million, five hundred fifty-five thousand, nine hundred ninety-one".