404209891 has 4 divisors (see below), whose sum is σ = 405712800. Its totient is φ = 402706984.

The previous prime is 404209879. The next prime is 404209903. The reversal of 404209891 is 198902404.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (404209879) and next prime (404209903).

It is a cyclic number.

It is not a de Polignac number, because 404209891 - 2¹⁷ = 404078819 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 404209891.

It is not an unprimeable number, because it can be changed into a prime (404209831) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 751051 + ... + 751588.

It is an arithmetic number, because the mean of its divisors is an integer number (101428200).

Almost surely, 2^404209891 is an apocalyptic number.

404209891 is a deficient number, since it is larger than the sum of its proper divisors (1502909).

404209891 is a wasteful number, since it uses less digits than its factorization.

404209891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1502908.

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 404209891 is about 20104.9717980404. The cubic root of 404209891 is about 739.3821791186.

The spelling of 404209891 in words is "four hundred four million, two hundred nine thousand, eight hundred ninety-one".