21256063 has 4 divisors (see below), whose sum is σ = 21266280. Its totient is φ = 21245848.

The previous prime is 21256057. The next prime is 21256087. The reversal of 21256063 is 36065212.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21256063 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21256013) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 745 + ... + 6562.

It is an arithmetic number, because the mean of its divisors is an integer number (5316570).

Almost surely, 2^21256063 is an apocalyptic number.

21256063 is a deficient number, since it is larger than the sum of its proper divisors (10217).

21256063 is an equidigital number, since it uses as much as digits as its factorization.

21256063 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10216.

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

The square root of 21256063 is about 4610.4298064280. The cubic root of 21256063 is about 277.0092530371.

The spelling of 21256063 in words is "twenty-one million, two hundred fifty-six thousand, sixty-three".