321638999021 has 2 divisors, whose sum is σ = 321638999022. Its totient is φ = 321638999020.

The previous prime is 321638998957. The next prime is 321638999041. The reversal of 321638999021 is 120999836123.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 269998708996 + 51640290025 = 519614^2 + 227245^2 .

It is a cyclic number.

It is not a de Polignac number, because 321638999021 - 2⁶ = 321638998957 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (321638999041) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160819499510 + 160819499511.

It is an arithmetic number, because the mean of its divisors is an integer number (160819499511).

Almost surely, 2^321638999021 is an apocalyptic number.

It is an amenable number.

321638999021 is a deficient number, since it is larger than the sum of its proper divisors (1).

321638999021 is an equidigital number, since it uses as much as digits as its factorization.

321638999021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1259712, while the sum is 53.

The spelling of 321638999021 in words is "three hundred twenty-one billion, six hundred thirty-eight million, nine hundred ninety-nine thousand, twenty-one".