391965869 has 2 divisors, whose sum is σ = 391965870. Its totient is φ = 391965868.

The previous prime is 391965859. The next prime is 391965929. The reversal of 391965869 is 968569193.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 268533769 + 123432100 = 16387^2 + 11110^2 .

It is a cyclic number.

It is not a de Polignac number, because 391965869 - 2²⁸ = 123530413 is a prime.

It is a super-2 number, since 2×391965869² = 307274484921850322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (391965859) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195982934 + 195982935.

It is an arithmetic number, because the mean of its divisors is an integer number (195982935).

Almost surely, 2^391965869 is an apocalyptic number.

It is an amenable number.

391965869 is a deficient number, since it is larger than the sum of its proper divisors (1).

391965869 is an equidigital number, since it uses as much as digits as its factorization.

391965869 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3149280, while the sum is 56.

The square root of 391965869 is about 19798.1279165481. The cubic root of 391965869 is about 731.8399006120.

The spelling of 391965869 in words is "three hundred ninety-one million, nine hundred sixty-five thousand, eight hundred sixty-nine".