401023991 has 2 divisors, whose sum is σ = 401023992. Its totient is φ = 401023990.

The previous prime is 401023981. The next prime is 401024009. The reversal of 401023991 is 199320104.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 401023991 - 2⁶ = 401023927 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 (401023921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200511995 + 200511996.

It is an arithmetic number, because the mean of its divisors is an integer number (200511996).

Almost surely, 2^401023991 is an apocalyptic number.

401023991 is a deficient number, since it is larger than the sum of its proper divisors (1).

401023991 is an equidigital number, since it uses as much as digits as its factorization.

401023991 is an evil number, because the sum of its binary digits is even.

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

The square root of 401023991 is about 20025.5834122255. The cubic root of 401023991 is about 737.4344998230.

The spelling of 401023991 in words is "four hundred one million, twenty-three thousand, nine hundred ninety-one".