398655581 has 2 divisors, whose sum is σ = 398655582. Its totient is φ = 398655580.

The previous prime is 398655563. The next prime is 398655601. The reversal of 398655581 is 185556893.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 279190681 + 119464900 = 16709^2 + 10930^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-398655581 is a prime.

It is a super-2 number, since 2×398655581² = 317852544524895122, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (398655541) 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, 199327790 + 199327791.

It is an arithmetic number, because the mean of its divisors is an integer number (199327791).

Almost surely, 2^398655581 is an apocalyptic number.

It is an amenable number.

398655581 is a deficient number, since it is larger than the sum of its proper divisors (1).

398655581 is an equidigital number, since it uses as much as digits as its factorization.

398655581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1296000, while the sum is 50.

The square root of 398655581 is about 19966.3612358386. The cubic root of 398655581 is about 735.9798928472.

The spelling of 398655581 in words is "three hundred ninety-eight million, six hundred fifty-five thousand, five hundred eighty-one".