21284047 has 8 divisors (see below), whose sum is σ = 22498560. Its totient is φ = 20079000.

The previous prime is 21284041. The next prime is 21284093. The reversal of 21284047 is 74048212.

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 21284047 - 2⁷ = 21283919 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21284041) 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, 2538 + ... + 7000.

It is an arithmetic number, because the mean of its divisors is an integer number (2812320).

Almost surely, 2^21284047 is an apocalyptic number.

21284047 is a deficient number, since it is larger than the sum of its proper divisors (1214513).

21284047 is a wasteful number, since it uses less digits than its factorization.

21284047 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4733.

The product of its (nonzero) digits is 3584, while the sum is 28.

The square root of 21284047 is about 4613.4636662707. The cubic root of 21284047 is about 277.1307623309.

The spelling of 21284047 in words is "twenty-one million, two hundred eighty-four thousand, forty-seven".