520771991 has 2 divisors, whose sum is σ = 520771992. Its totient is φ = 520771990.

The previous prime is 520771981. The next prime is 520772023. The reversal of 520771991 is 199177025.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 520771991 - 2¹⁴ = 520755607 is a prime.

It is a super-2 number, since 2×520771991² = 542406933220208162, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (520771921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260385995 + 260385996.

It is an arithmetic number, because the mean of its divisors is an integer number (260385996).

Almost surely, 2^520771991 is an apocalyptic number.

520771991 is a deficient number, since it is larger than the sum of its proper divisors (1).

520771991 is an equidigital number, since it uses as much as digits as its factorization.

520771991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 39690, while the sum is 41.

The square root of 520771991 is about 22820.4292466202. The cubic root of 520771991 is about 804.5428990663.

The spelling of 520771991 in words is "five hundred twenty million, seven hundred seventy-one thousand, nine hundred ninety-one".