21290903 has 2 divisors, whose sum is σ = 21290904. Its totient is φ = 21290902.

The previous prime is 21290839. The next prime is 21290921. The reversal of 21290903 is 30909212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21290903 - 2⁶ = 21290839 is a prime.

It is a Chen prime.

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

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21290923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10645451 + 10645452.

It is an arithmetic number, because the mean of its divisors is an integer number (10645452).

Almost surely, 2^21290903 is an apocalyptic number.

21290903 is a deficient number, since it is larger than the sum of its proper divisors (1).

21290903 is an equidigital number, since it uses as much as digits as its factorization.

21290903 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 972, while the sum is 26.

The square root of 21290903 is about 4614.2066490351. The cubic root of 21290903 is about 277.1605155155.

The spelling of 21290903 in words is "twenty-one million, two hundred ninety thousand, nine hundred three".