21084281 has 8 divisors (see below), whose sum is σ = 22344000. Its totient is φ = 19839600.

The previous prime is 21084269. The next prime is 21084289. The reversal of 21084281 is 18248012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21084281 is a prime.

It is a super-2 number, since 2×21084281² = 889093810573922, which contains 22 as substring.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21084281.

It is not an unprimeable number, because it can be changed into a prime (21084289) 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, 806 + ... + 6543.

It is an arithmetic number, because the mean of its divisors is an integer number (2793000).

Almost surely, 2^21084281 is an apocalyptic number.

It is an amenable number.

21084281 is a deficient number, since it is larger than the sum of its proper divisors (1259719).

21084281 is a wasteful number, since it uses less digits than its factorization.

21084281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7519.

The product of its (nonzero) digits is 1024, while the sum is 26.

The square root of 21084281 is about 4591.7622978547. The cubic root of 21084281 is about 276.2610120983.

The spelling of 21084281 in words is "twenty-one million, eighty-four thousand, two hundred eighty-one".