521122991 has 2 divisors, whose sum is σ = 521122992. Its totient is φ = 521122990.

The previous prime is 521122969. The next prime is 521122993. The reversal of 521122991 is 199221125.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-521122991 is a prime.

Together with 521122993, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (521122993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260561495 + 260561496.

It is an arithmetic number, because the mean of its divisors is an integer number (260561496).

Almost surely, 2^521122991 is an apocalyptic number.

521122991 is a deficient number, since it is larger than the sum of its proper divisors (1).

521122991 is an equidigital number, since it uses as much as digits as its factorization.

521122991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3240, while the sum is 32.

The square root of 521122991 is about 22828.1184288149. The cubic root of 521122991 is about 804.7236122777.

The spelling of 521122991 in words is "five hundred twenty-one million, one hundred twenty-two thousand, nine hundred ninety-one".