21493603 has 2 divisors, whose sum is σ = 21493604. Its totient is φ = 21493602.

The previous prime is 21493583. The next prime is 21493613. The reversal of 21493603 is 30639412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21493603 - 2⁹ = 21493091 is a prime.

It is not a weakly prime, because it can be changed into another prime (21493613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10746801 + 10746802.

It is an arithmetic number, because the mean of its divisors is an integer number (10746802).

Almost surely, 2^21493603 is an apocalyptic number.

21493603 is a deficient number, since it is larger than the sum of its proper divisors (1).

21493603 is an equidigital number, since it uses as much as digits as its factorization.

21493603 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3888, while the sum is 28.

The square root of 21493603 is about 4636.1193901797. The cubic root of 21493603 is about 278.0373075891.

The spelling of 21493603 in words is "twenty-one million, four hundred ninety-three thousand, six hundred three".