21265619 has 2 divisors, whose sum is σ = 21265620. Its totient is φ = 21265618.

The previous prime is 21265603. The next prime is 21265631. The reversal of 21265619 is 91656212.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21265619 - 2⁴ = 21265603 is a prime.

It is a super-2 number, since 2×21265619² = 904453102906322, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21265669) 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, 10632809 + 10632810.

It is an arithmetic number, because the mean of its divisors is an integer number (10632810).

Almost surely, 2^21265619 is an apocalyptic number.

21265619 is a deficient number, since it is larger than the sum of its proper divisors (1).

21265619 is an equidigital number, since it uses as much as digits as its factorization.

21265619 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6480, while the sum is 32.

The square root of 21265619 is about 4611.4660358719. The cubic root of 21265619 is about 277.0507581179.

It can be divided in two parts, 2 and 1265619, that added together give a palindrome (1265621).

The spelling of 21265619 in words is "twenty-one million, two hundred sixty-five thousand, six hundred nineteen".