521194021 has 2 divisors, whose sum is σ = 521194022. Its totient is φ = 521194020.

The previous prime is 521193947. The next prime is 521194033. The reversal of 521194021 is 120491125.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 460960900 + 60233121 = 21470^2 + 7761^2 .

It is a cyclic number.

It is not a de Polignac number, because 521194021 - 2⁹ = 521193509 is a prime.

It is a super-2 number, since 2×521194021² = 543286415052296882, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (521197021) 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, 260597010 + 260597011.

It is an arithmetic number, because the mean of its divisors is an integer number (260597011).

Almost surely, 2^521194021 is an apocalyptic number.

It is an amenable number.

521194021 is a deficient number, since it is larger than the sum of its proper divisors (1).

521194021 is an equidigital number, since it uses as much as digits as its factorization.

521194021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 720, while the sum is 25.

The square root of 521194021 is about 22829.6741325845. The cubic root of 521194021 is about 804.7601723748.

The spelling of 521194021 in words is "five hundred twenty-one million, one hundred ninety-four thousand, twenty-one".