21286345 has 4 divisors (see below), whose sum is σ = 25543620. Its totient is φ = 17029072.

The previous prime is 21286303. The next prime is 21286351. The reversal of 21286345 is 54368212.

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

It can be written as a sum of positive squares in 2 ways, for example, as 5053504 + 16232841 = 2248^2 + 4029^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21286345 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2128630 + ... + 2128639.

It is an arithmetic number, because the mean of its divisors is an integer number (6385905).

Almost surely, 2^21286345 is an apocalyptic number.

It is an amenable number.

21286345 is a deficient number, since it is larger than the sum of its proper divisors (4257275).

21286345 is an equidigital number, since it uses as much as digits as its factorization.

21286345 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4257274.

The product of its digits is 11520, while the sum is 31.

The square root of 21286345 is about 4613.7127132061. The cubic root of 21286345 is about 277.1407357408.

The spelling of 21286345 in words is "twenty-one million, two hundred eighty-six thousand, three hundred forty-five".