855409391 has 2 divisors, whose sum is σ = 855409392. Its totient is φ = 855409390.

The previous prime is 855409369. The next prime is 855409397. The reversal of 855409391 is 193904558.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-855409391 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (855409397) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 427704695 + 427704696.

It is an arithmetic number, because the mean of its divisors is an integer number (427704696).

Almost surely, 2^855409391 is an apocalyptic number.

855409391 is a deficient number, since it is larger than the sum of its proper divisors (1).

855409391 is an equidigital number, since it uses as much as digits as its factorization.

855409391 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 194400, while the sum is 44.

The square root of 855409391 is about 29247.3826350325. The cubic root of 855409391 is about 949.2734577922.

The spelling of 855409391 in words is "eight hundred fifty-five million, four hundred nine thousand, three hundred ninety-one".