391894289 has 2 divisors, whose sum is σ = 391894290. Its totient is φ = 391894288.

The previous prime is 391894271. The next prime is 391894291. The reversal of 391894289 is 982498193.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 304153600 + 87740689 = 17440^2 + 9367^2 .

It is a cyclic number.

It is not a de Polignac number, because 391894289 - 2²⁴ = 375117073 is a prime.

It is a super-2 number, since 2×391894289² = 307162267501631042, which contains 22 as substring.

Together with 391894291, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 391894289.

It is not a weakly prime, because it can be changed into another prime (391891289) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195947144 + 195947145.

It is an arithmetic number, because the mean of its divisors is an integer number (195947145).

Almost surely, 2^391894289 is an apocalyptic number.

It is an amenable number.

391894289 is a deficient number, since it is larger than the sum of its proper divisors (1).

391894289 is an equidigital number, since it uses as much as digits as its factorization.

391894289 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1119744, while the sum is 53.

The square root of 391894289 is about 19796.3200873294. The cubic root of 391894289 is about 731.7953488680.

The spelling of 391894289 in words is "three hundred ninety-one million, eight hundred ninety-four thousand, two hundred eighty-nine".