391394881 has 2 divisors, whose sum is σ = 391394882. Its totient is φ = 391394880.

The previous prime is 391394827. The next prime is 391394891. The reversal of 391394881 is 188493193.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 363474225 + 27920656 = 19065^2 + 5284^2 .

It is a cyclic number.

It is not a de Polignac number, because 391394881 - 2⁷ = 391394753 is a prime.

It is a super-2 number, since 2×391394881² = 306379905746008322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (391394821) 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, 195697440 + 195697441.

It is an arithmetic number, because the mean of its divisors is an integer number (195697441).

Almost surely, 2^391394881 is an apocalyptic number.

It is an amenable number.

391394881 is a deficient number, since it is larger than the sum of its proper divisors (1).

391394881 is an equidigital number, since it uses as much as digits as its factorization.

391394881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 186624, while the sum is 46.

The square root of 391394881 is about 19783.7024088010. The cubic root of 391394881 is about 731.4843638105.

The spelling of 391394881 in words is "three hundred ninety-one million, three hundred ninety-four thousand, eight hundred eighty-one".