391989965 has 8 divisors (see below), whose sum is σ = 478099608. Its totient is φ = 308450880.

The previous prime is 391989959. The next prime is 391989991. The reversal of 391989965 is 569989193.

It can be written as a sum of positive squares in 4 ways, for example, as 38775529 + 353214436 = 6227^2 + 18794^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 391989965 - 2¹⁴ = 391973581 is a prime.

It is a super-2 number, since 2×391989965² = 307312265321402450, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 642302 + ... + 642911.

It is an arithmetic number, because the mean of its divisors is an integer number (59762451).

Almost surely, 2^391989965 is an apocalyptic number.

It is an amenable number.

391989965 is a deficient number, since it is larger than the sum of its proper divisors (86109643).

391989965 is a wasteful number, since it uses less digits than its factorization.

391989965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1285279.

The product of its digits is 4723920, while the sum is 59.

The square root of 391989965 is about 19798.7364495818. The cubic root of 391989965 is about 731.8548968607.

The spelling of 391989965 in words is "three hundred ninety-one million, nine hundred eighty-nine thousand, nine hundred sixty-five".