400691891 has 2 divisors, whose sum is σ = 400691892. Its totient is φ = 400691890.

The previous prime is 400691881. The next prime is 400691897. The reversal of 400691891 is 198196004.

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-400691891 is a prime.

It is not a weakly prime, because it can be changed into another prime (400691897) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200345945 + 200345946.

It is an arithmetic number, because the mean of its divisors is an integer number (200345946).

Almost surely, 2^400691891 is an apocalyptic number.

400691891 is a deficient number, since it is larger than the sum of its proper divisors (1).

400691891 is an equidigital number, since it uses as much as digits as its factorization.

400691891 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15552, while the sum is 38.

The square root of 400691891 is about 20017.2898015690. The cubic root of 400691891 is about 737.2308797258.

The spelling of 400691891 in words is "four hundred million, six hundred ninety-one thousand, eight hundred ninety-one".