857220191 has 2 divisors, whose sum is σ = 857220192. Its totient is φ = 857220190.

The previous prime is 857220187. The next prime is 857220209. The reversal of 857220191 is 191022758.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 857220191 - 2² = 857220187 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (857220151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 428610095 + 428610096.

It is an arithmetic number, because the mean of its divisors is an integer number (428610096).

Almost surely, 2^857220191 is an apocalyptic number.

857220191 is a deficient number, since it is larger than the sum of its proper divisors (1).

857220191 is an equidigital number, since it uses as much as digits as its factorization.

857220191 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10080, while the sum is 35.

The square root of 857220191 is about 29278.3228857119. The cubic root of 857220191 is about 949.9428187189.

The spelling of 857220191 in words is "eight hundred fifty-seven million, two hundred twenty thousand, one hundred ninety-one".