4231991 has 2 divisors, whose sum is σ = 4231992. Its totient is φ = 4231990.

The previous prime is 4231967. The next prime is 4231993. The reversal of 4231991 is 1991324.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-4231991 is a prime.

Together with 4231993, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (4231993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2115995 + 2115996.

It is an arithmetic number, because the mean of its divisors is an integer number (2115996).

Almost surely, 2^4231991 is an apocalyptic number.

4231991 is a deficient number, since it is larger than the sum of its proper divisors (1).

4231991 is an equidigital number, since it uses as much as digits as its factorization.

4231991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1944, while the sum is 29.

The square root of 4231991 is about 2057.1803518408. The cubic root of 4231991 is about 161.7514733185.

The spelling of 4231991 in words is "four million, two hundred thirty-one thousand, nine hundred ninety-one".