21265603 has 2 divisors, whose sum is σ = 21265604. Its totient is φ = 21265602.

The previous prime is 21265577. The next prime is 21265619. The reversal of 21265603 is 30656212.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21265603 is a prime.

It is not a weakly prime, because it can be changed into another prime (21265633) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10632801 + 10632802.

It is an arithmetic number, because the mean of its divisors is an integer number (10632802).

Almost surely, 2^21265603 is an apocalyptic number.

21265603 is a deficient number, since it is larger than the sum of its proper divisors (1).

21265603 is an equidigital number, since it uses as much as digits as its factorization.

21265603 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2160, while the sum is 25.

The square root of 21265603 is about 4611.4643010653. The cubic root of 21265603 is about 277.0506886347.

The spelling of 21265603 in words is "twenty-one million, two hundred sixty-five thousand, six hundred three".