20998903 has 4 divisors (see below), whose sum is σ = 21184848. Its totient is φ = 20812960.

The previous prime is 20998897. The next prime is 20998909. The reversal of 20998903 is 30989902.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 30989902 = 2 ⋅15494951.

It is an interprime number because it is at equal distance from previous prime (20998897) and next prime (20998909).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20998903 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 (20998909) 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, 92803 + ... + 93028.

It is an arithmetic number, because the mean of its divisors is an integer number (5296212).

Almost surely, 2^20998903 is an apocalyptic number.

20998903 is a deficient number, since it is larger than the sum of its proper divisors (185945).

20998903 is a wasteful number, since it uses less digits than its factorization.

20998903 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 185944.

The product of its (nonzero) digits is 34992, while the sum is 40.

The square root of 20998903 is about 4582.4560008799. The cubic root of 20998903 is about 275.8876135230.

Subtracting 20998903 from its reverse (30989902), we obtain a palindrome (9990999).

The spelling of 20998903 in words is "twenty million, nine hundred ninety-eight thousand, nine hundred three".