399838515221 has 2 divisors, whose sum is σ = 399838515222. Its totient is φ = 399838515220.

The previous prime is 399838515199. The next prime is 399838515301. The reversal of 399838515221 is 122515838993.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 392947191025 + 6891324196 = 626855^2 + 83014^2 .

It is a cyclic number.

It is not a de Polignac number, because 399838515221 - 2²⁶ = 399771406357 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (399838515121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199919257610 + 199919257611.

It is an arithmetic number, because the mean of its divisors is an integer number (199919257611).

Almost surely, 2^399838515221 is an apocalyptic number.

It is an amenable number.

399838515221 is a deficient number, since it is larger than the sum of its proper divisors (1).

399838515221 is an equidigital number, since it uses as much as digits as its factorization.

399838515221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4665600, while the sum is 56.

The spelling of 399838515221 in words is "three hundred ninety-nine billion, eight hundred thirty-eight million, five hundred fifteen thousand, two hundred twenty-one".