391989318 has 32 divisors (see below), whose sum is σ = 914265600. Its totient is φ = 111996360.

The previous prime is 391989289. The next prime is 391989331. The reversal of 391989318 is 813989193.

It is a happy number.

It is a super-2 number, since 2×391989318² = 307311250852210248, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 93178 + ... + 97293.

It is an arithmetic number, because the mean of its divisors is an integer number (28570800).

Almost surely, 2^391989318 is an apocalyptic number.

391989318 is an abundant number, since it is smaller than the sum of its proper divisors (522276282).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

391989318 is a wasteful number, since it uses less digits than its factorization.

391989318 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 190497 (or 190483 counting only the distinct ones).

The product of its digits is 419904, while the sum is 51.

The square root of 391989318 is about 19798.7201101485. The cubic root of 391989318 is about 731.8544942055.

It can be divided in two parts, 39198 and 9318, that added together give a triangular number (48516 = T₃₁₁).

The spelling of 391989318 in words is "three hundred ninety-one million, nine hundred eighty-nine thousand, three hundred eighteen".