21266281 has 4 divisors (see below), whose sum is σ = 21393792. Its totient is φ = 21138772.

The previous prime is 21266239. The next prime is 21266291. The reversal of 21266281 is 18266212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21266281 is a prime.

It is a super-2 number, since 2×21266281² = 904509415141922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21266291) 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, 63505 + ... + 63838.

It is an arithmetic number, because the mean of its divisors is an integer number (5348448).

Almost surely, 2^21266281 is an apocalyptic number.

It is an amenable number.

21266281 is a deficient number, since it is larger than the sum of its proper divisors (127511).

21266281 is a wasteful number, since it uses less digits than its factorization.

21266281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127510.

The product of its digits is 2304, while the sum is 28.

The square root of 21266281 is about 4611.5378129210. The cubic root of 21266281 is about 277.0536329570.

The spelling of 21266281 in words is "twenty-one million, two hundred sixty-six thousand, two hundred eighty-one".