19408991 has 4 divisors (see below), whose sum is σ = 22181712. Its totient is φ = 16636272.

The previous prime is 19408981. The next prime is 19408997. The reversal of 19408991 is 19980491.

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 19408991 - 2¹⁸ = 19146847 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19408997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1386350 + ... + 1386363.

It is an arithmetic number, because the mean of its divisors is an integer number (5545428).

Almost surely, 2^19408991 is an apocalyptic number.

19408991 is a deficient number, since it is larger than the sum of its proper divisors (2772721).

19408991 is an equidigital number, since it uses as much as digits as its factorization.

19408991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2772720.

The product of its (nonzero) digits is 23328, while the sum is 41.

The square root of 19408991 is about 4405.5636415787. The cubic root of 19408991 is about 268.7412417553.

The spelling of 19408991 in words is "nineteen million, four hundred eight thousand, nine hundred ninety-one".