19991903 has 4 divisors (see below), whose sum is σ = 20005128. Its totient is φ = 19978680.

The previous prime is 19991893. The next prime is 19991911. The reversal of 19991903 is 30919991.

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 19991903 - 2¹⁰ = 19990879 is a prime.

It is a super-2 number, since 2×19991903² = 799352371122818, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19991963) 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, 4001 + ... + 7482.

It is an arithmetic number, because the mean of its divisors is an integer number (5001282).

Almost surely, 2^19991903 is an apocalyptic number.

19991903 is a deficient number, since it is larger than the sum of its proper divisors (13225).

19991903 is a wasteful number, since it uses less digits than its factorization.

19991903 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13224.

The product of its (nonzero) digits is 19683, while the sum is 41.

The square root of 19991903 is about 4471.2305912355. The cubic root of 19991903 is about 271.4051256493.

The spelling of 19991903 in words is "nineteen million, nine hundred ninety-one thousand, nine hundred three".