408990991 has 4 divisors (see below), whose sum is σ = 426773232. Its totient is φ = 391208752.

The previous prime is 408990977. The next prime is 408990997. The reversal of 408990991 is 199099804.

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

It is a cyclic number.

It is not a de Polignac number, because 408990991 - 2⁹ = 408990479 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (408990997) 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, 8891086 + ... + 8891131.

It is an arithmetic number, because the mean of its divisors is an integer number (106693308).

Almost surely, 2^408990991 is an apocalyptic number.

408990991 is a deficient number, since it is larger than the sum of its proper divisors (17782241).

408990991 is a wasteful number, since it uses less digits than its factorization.

408990991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17782240.

The product of its (nonzero) digits is 209952, while the sum is 49.

The square root of 408990991 is about 20223.5256817401. The cubic root of 408990991 is about 742.2859618786.

The spelling of 408990991 in words is "four hundred eight million, nine hundred ninety thousand, nine hundred ninety-one".