398561021 has 2 divisors, whose sum is σ = 398561022. Its totient is φ = 398561020.

The previous prime is 398560999. The next prime is 398561087. The reversal of 398561021 is 120165893.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 223951225 + 174609796 = 14965^2 + 13214^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-398561021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (398561921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199280510 + 199280511.

It is an arithmetic number, because the mean of its divisors is an integer number (199280511).

Almost surely, 2^398561021 is an apocalyptic number.

It is an amenable number.

398561021 is a deficient number, since it is larger than the sum of its proper divisors (1).

398561021 is an equidigital number, since it uses as much as digits as its factorization.

398561021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12960, while the sum is 35.

The square root of 398561021 is about 19963.9931126015. The cubic root of 398561021 is about 735.9216974481.

The spelling of 398561021 in words is "three hundred ninety-eight million, five hundred sixty-one thousand, twenty-one".