398989831 has 4 divisors (see below), whose sum is σ = 400248792. Its totient is φ = 397730872.

The previous prime is 398989807. The next prime is 398989841. The reversal of 398989831 is 138989893.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 138989893 = 7 ⋅19855699.

It is a cyclic number.

It is not a de Polignac number, because 398989831 - 2⁹ = 398989319 is a prime.

It is a super-2 number, since 2×398989831² = 318385770482817122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (398989841) 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 in 3 ways as a sum of consecutive naturals, for example, 629005 + ... + 629638.

It is an arithmetic number, because the mean of its divisors is an integer number (100062198).

Almost surely, 2^398989831 is an apocalyptic number.

398989831 is a deficient number, since it is larger than the sum of its proper divisors (1258961).

398989831 is a wasteful number, since it uses less digits than its factorization.

398989831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1258960.

The product of its digits is 3359232, while the sum is 58.

The square root of 398989831 is about 19974.7298104380. The cubic root of 398989831 is about 736.1855277948.

It can be divided in two parts, 39898 and 9831, that added together give a square (49729 = 223²).

The spelling of 398989831 in words is "three hundred ninety-eight million, nine hundred eighty-nine thousand, eight hundred thirty-one".