398957981 has 2 divisors, whose sum is σ = 398957982. Its totient is φ = 398957980.

The previous prime is 398957963. The next prime is 398957987. The reversal of 398957981 is 189759893.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 387735481 + 11222500 = 19691^2 + 3350^2 .

It is a cyclic number.

It is not a de Polignac number, because 398957981 - 2¹⁴ = 398941597 is a prime.

It is a super-2 number, since 2×398957981² = 318334941207192722, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 398957981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (398957987) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199478990 + 199478991.

It is an arithmetic number, because the mean of its divisors is an integer number (199478991).

Almost surely, 2^398957981 is an apocalyptic number.

It is an amenable number.

398957981 is a deficient number, since it is larger than the sum of its proper divisors (1).

398957981 is an equidigital number, since it uses as much as digits as its factorization.

398957981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4898880, while the sum is 59.

The square root of 398957981 is about 19973.9325371846. The cubic root of 398957981 is about 736.1659382120.

The spelling of 398957981 in words is "three hundred ninety-eight million, nine hundred fifty-seven thousand, nine hundred eighty-one".