21281449 has 8 divisors (see below), whose sum is σ = 24615360. Its totient is φ = 18020976.

The previous prime is 21281441. The next prime is 21281453. The reversal of 21281449 is 94418212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21281449 - 2³ = 21281441 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21281449.

It is not an unprimeable number, because it can be changed into a prime (21281441) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17734 + ... + 18895.

It is an arithmetic number, because the mean of its divisors is an integer number (3076920).

Almost surely, 2^21281449 is an apocalyptic number.

It is an amenable number.

21281449 is a deficient number, since it is larger than the sum of its proper divisors (3333911).

21281449 is an equidigital number, since it uses as much as digits as its factorization.

21281449 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36719.

The product of its digits is 4608, while the sum is 31.

The square root of 21281449 is about 4613.1820904881. The cubic root of 21281449 is about 277.1194860447.

The spelling of 21281449 in words is "twenty-one million, two hundred eighty-one thousand, four hundred forty-nine".