20391903 has 24 divisors (see below), whose sum is σ = 33785856. Its totient is φ = 11610000.

The previous prime is 20391887. The next prime is 20391907. The reversal of 20391903 is 30919302.

It is not a de Polignac number, because 20391903 - 2⁴ = 20391887 is a prime.

It is a super-2 number, since 2×20391903² = 831659415922818, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20391907) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 26778 + ... + 27528.

It is an arithmetic number, because the mean of its divisors is an integer number (1407744).

Almost surely, 2^20391903 is an apocalyptic number.

20391903 is a deficient number, since it is larger than the sum of its proper divisors (13393953).

20391903 is a wasteful number, since it uses less digits than its factorization.

20391903 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1195 (or 1192 counting only the distinct ones).

The product of its (nonzero) digits is 1458, while the sum is 27.

The square root of 20391903 is about 4515.7394743275. The cubic root of 20391903 is about 273.2032861759.

The spelling of 20391903 in words is "twenty million, three hundred ninety-one thousand, nine hundred three".