201111991 has 2 divisors, whose sum is σ = 201111992. Its totient is φ = 201111990.

The previous prime is 201111971. The next prime is 201112019. The reversal of 201111991 is 199111102.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 201111991 - 2¹¹ = 201109943 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (201111971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 100555995 + 100555996.

It is an arithmetic number, because the mean of its divisors is an integer number (100555996).

Almost surely, 2^201111991 is an apocalyptic number.

201111991 is a deficient number, since it is larger than the sum of its proper divisors (1).

201111991 is an equidigital number, since it uses as much as digits as its factorization.

201111991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 162, while the sum is 25.

The square root of 201111991 is about 14181.3959468030. The cubic root of 201111991 is about 585.8853722837.

The spelling of 201111991 in words is "two hundred one million, one hundred eleven thousand, nine hundred ninety-one".