21250903 has 4 divisors (see below), whose sum is σ = 21936448. Its totient is φ = 20565360.

The previous prime is 21250877. The next prime is 21250961. The reversal of 21250903 is 30905212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21250903 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21251903) 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, 342726 + ... + 342787.

It is an arithmetic number, because the mean of its divisors is an integer number (5484112).

Almost surely, 2^21250903 is an apocalyptic number.

21250903 is a deficient number, since it is larger than the sum of its proper divisors (685545).

21250903 is an equidigital number, since it uses as much as digits as its factorization.

21250903 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 685544.

The product of its (nonzero) digits is 540, while the sum is 22.

The square root of 21250903 is about 4609.8701717077. The cubic root of 21250903 is about 276.9868361636.

It can be divided in two parts, 212 and 50903, that added together give a palindrome (51115).

The spelling of 21250903 in words is "twenty-one million, two hundred fifty thousand, nine hundred three".