901991191 has 2 divisors, whose sum is σ = 901991192. Its totient is φ = 901991190.

The previous prime is 901991099. The next prime is 901991243. The reversal of 901991191 is 191199109.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 901991191 - 2⁷ = 901991063 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (901991891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 450995595 + 450995596.

It is an arithmetic number, because the mean of its divisors is an integer number (450995596).

Almost surely, 2^901991191 is an apocalyptic number.

901991191 is a deficient number, since it is larger than the sum of its proper divisors (1).

901991191 is an equidigital number, since it uses as much as digits as its factorization.

901991191 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6561, while the sum is 40.

The square root of 901991191 is about 30033.1681811959. The cubic root of 901991191 is about 966.2008874689.

The spelling of 901991191 in words is "nine hundred one million, nine hundred ninety-one thousand, one hundred ninety-one".