21601903 has 2 divisors, whose sum is σ = 21601904. Its totient is φ = 21601902.

The previous prime is 21601891. The next prime is 21601913. The reversal of 21601903 is 30910612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21601903 - 2¹⁷ = 21470831 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21601913) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10800951 + 10800952.

It is an arithmetic number, because the mean of its divisors is an integer number (10800952).

Almost surely, 2^21601903 is an apocalyptic number.

21601903 is a deficient number, since it is larger than the sum of its proper divisors (1).

21601903 is an equidigital number, since it uses as much as digits as its factorization.

21601903 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 324, while the sum is 22.

The square root of 21601903 is about 4647.7847411428. The cubic root of 21601903 is about 278.5035084280.

The spelling of 21601903 in words is "twenty-one million, six hundred one thousand, nine hundred three".