21265687 has 2 divisors, whose sum is σ = 21265688. Its totient is φ = 21265686.

The previous prime is 21265681. The next prime is 21265697. The reversal of 21265687 is 78656212.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21265687 - 2¹⁵ = 21232919 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21265681) 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, 10632843 + 10632844.

It is an arithmetic number, because the mean of its divisors is an integer number (10632844).

Almost surely, 2^21265687 is an apocalyptic number.

21265687 is a deficient number, since it is larger than the sum of its proper divisors (1).

21265687 is an equidigital number, since it uses as much as digits as its factorization.

21265687 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 40320, while the sum is 37.

The square root of 21265687 is about 4611.4734087925. The cubic root of 21265687 is about 277.0510534214.

It can be divided in two parts, 21265 and 687, that added together give a cube (21952 = 28³).

The spelling of 21265687 in words is "twenty-one million, two hundred sixty-five thousand, six hundred eighty-seven".