521167021 has 2 divisors, whose sum is σ = 521167022. Its totient is φ = 521167020.

The previous prime is 521167019. The next prime is 521167057. The reversal of 521167021 is 120761125.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 395413225 + 125753796 = 19885^2 + 11214^2 .

It is a cyclic number.

It is not a de Polignac number, because 521167021 - 2¹ = 521167019 is a prime.

Together with 521167019, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (521167061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260583510 + 260583511.

It is an arithmetic number, because the mean of its divisors is an integer number (260583511).

Almost surely, 2^521167021 is an apocalyptic number.

It is an amenable number.

521167021 is a deficient number, since it is larger than the sum of its proper divisors (1).

521167021 is an equidigital number, since it uses as much as digits as its factorization.

521167021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 840, while the sum is 25.

The square root of 521167021 is about 22829.0827892844. The cubic root of 521167021 is about 804.7462755027.

The spelling of 521167021 in words is "five hundred twenty-one million, one hundred sixty-seven thousand, twenty-one".