123271991 has 2 divisors, whose sum is σ = 123271992. Its totient is φ = 123271990.

The previous prime is 123271987. The next prime is 123271999. The reversal of 123271991 is 199172321.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 123271991 - 2² = 123271987 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (123271999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 61635995 + 61635996.

It is an arithmetic number, because the mean of its divisors is an integer number (61635996).

Almost surely, 2^123271991 is an apocalyptic number.

123271991 is a deficient number, since it is larger than the sum of its proper divisors (1).

123271991 is an equidigital number, since it uses as much as digits as its factorization.

123271991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6804, while the sum is 35.

The square root of 123271991 is about 11102.7920362403. The cubic root of 123271991 is about 497.6852887597.

The spelling of 123271991 in words is "one hundred twenty-three million, two hundred seventy-one thousand, nine hundred ninety-one".