398735621 has 2 divisors, whose sum is σ = 398735622. Its totient is φ = 398735620.

The previous prime is 398735593. The next prime is 398735647. The reversal of 398735621 is 126537893.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 386908900 + 11826721 = 19670^2 + 3439^2 .

It is an emirp because it is prime and its reverse (126537893) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 398735621 - 2¹⁰ = 398734597 is a prime.

It is a super-3 number, since 3×398735621³ (a number of 27 digits) contains 333 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (398735651) 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, 199367810 + 199367811.

It is an arithmetic number, because the mean of its divisors is an integer number (199367811).

Almost surely, 2^398735621 is an apocalyptic number.

It is an amenable number.

398735621 is a deficient number, since it is larger than the sum of its proper divisors (1).

398735621 is an equidigital number, since it uses as much as digits as its factorization.

398735621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 272160, while the sum is 44.

The square root of 398735621 is about 19968.3655064705. The cubic root of 398735621 is about 736.0291449598.

The spelling of 398735621 in words is "three hundred ninety-eight million, seven hundred thirty-five thousand, six hundred twenty-one".