108211991 has 2 divisors, whose sum is σ = 108211992. Its totient is φ = 108211990.

The previous prime is 108211967. The next prime is 108212009. The reversal of 108211991 is 199112801.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-108211991 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (108211391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 54105995 + 54105996.

It is an arithmetic number, because the mean of its divisors is an integer number (54105996).

Almost surely, 2^108211991 is an apocalyptic number.

108211991 is a deficient number, since it is larger than the sum of its proper divisors (1).

108211991 is an equidigital number, since it uses as much as digits as its factorization.

108211991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1296, while the sum is 32.

The square root of 108211991 is about 10402.4992670031. The cubic root of 108211991 is about 476.5316996617.

The spelling of 108211991 in words is "one hundred eight million, two hundred eleven thousand, nine hundred ninety-one".