21331903 has 2 divisors, whose sum is σ = 21331904. Its totient is φ = 21331902.

The previous prime is 21331901. The next prime is 21331963. The reversal of 21331903 is 30913312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21331903 - 2¹ = 21331901 is a prime.

Together with 21331901, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21331901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10665951 + 10665952.

It is an arithmetic number, because the mean of its divisors is an integer number (10665952).

Almost surely, 2^21331903 is an apocalyptic number.

21331903 is a deficient number, since it is larger than the sum of its proper divisors (1).

21331903 is an equidigital number, since it uses as much as digits as its factorization.

21331903 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 486, while the sum is 22.

The square root of 21331903 is about 4618.6473127962. The cubic root of 21331903 is about 277.3383112408.

The spelling of 21331903 in words is "twenty-one million, three hundred thirty-one thousand, nine hundred three".