21265873 has 2 divisors, whose sum is σ = 21265874. Its totient is φ = 21265872.

The previous prime is 21265859. The next prime is 21265877. The reversal of 21265873 is 37856212.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20367169 + 898704 = 4513^2 + 948^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21265873 is a prime.

It is not a weakly prime, because it can be changed into another prime (21265877) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10632936 + 10632937.

It is an arithmetic number, because the mean of its divisors is an integer number (10632937).

Almost surely, 2^21265873 is an apocalyptic number.

It is an amenable number.

21265873 is a deficient number, since it is larger than the sum of its proper divisors (1).

21265873 is an equidigital number, since it uses as much as digits as its factorization.

21265873 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20160, while the sum is 34.

The square root of 21265873 is about 4611.4935758385. The cubic root of 21265873 is about 277.0518611599.

The spelling of 21265873 in words is "twenty-one million, two hundred sixty-five thousand, eight hundred seventy-three".