111021991 has 2 divisors, whose sum is σ = 111021992. Its totient is φ = 111021990.

The previous prime is 111021971. The next prime is 111022033. The reversal of 111021991 is 199120111.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 111021991 - 2⁷ = 111021863 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (111021971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 55510995 + 55510996.

It is an arithmetic number, because the mean of its divisors is an integer number (55510996).

Almost surely, 2^111021991 is an apocalyptic number.

111021991 is a deficient number, since it is larger than the sum of its proper divisors (1).

111021991 is an equidigital number, since it uses as much as digits as its factorization.

111021991 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 111021991 is about 10536.6973478410. The cubic root of 111021991 is about 480.6212889471.

The spelling of 111021991 in words is "one hundred eleven million, twenty-one thousand, nine hundred ninety-one".