19891408 has 20 divisors (see below), whose sum is σ = 38644228. Its totient is φ = 9918720.

The previous prime is 19891393. The next prime is 19891409. The reversal of 19891408 is 80419891.

It can be written as a sum of positive squares in 2 ways, for example, as 6290064 + 13601344 = 2508^2 + 3688^2 .

It is a super-2 number, since 2×19891408² = 791336224444928, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19891409) 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, 5260 + ... + 8212.

Almost surely, 2^19891408 is an apocalyptic number.

It is an amenable number.

19891408 is a deficient number, since it is larger than the sum of its proper divisors (18752820).

19891408 is a wasteful number, since it uses less digits than its factorization.

19891408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3382 (or 3376 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 40.

The square root of 19891408 is about 4459.9784752844. The cubic root of 19891408 is about 270.9495964320.

The spelling of 19891408 in words is "nineteen million, eight hundred ninety-one thousand, four hundred eight".