21268159 has 4 divisors (see below), whose sum is σ = 23201640. Its totient is φ = 19334680.

The previous prime is 21268157. The next prime is 21268171. The reversal of 21268159 is 95186212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21268159 - 2¹ = 21268157 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21268151) 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 in 3 ways as a sum of consecutive naturals, for example, 966724 + ... + 966745.

It is an arithmetic number, because the mean of its divisors is an integer number (5800410).

Almost surely, 2^21268159 is an apocalyptic number.

21268159 is a deficient number, since it is larger than the sum of its proper divisors (1933481).

21268159 is a wasteful number, since it uses less digits than its factorization.

21268159 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1933480.

The product of its digits is 8640, while the sum is 34.

The square root of 21268159 is about 4611.7414281375. The cubic root of 21268159 is about 277.0617881427.

The spelling of 21268159 in words is "twenty-one million, two hundred sixty-eight thousand, one hundred fifty-nine".