21147793 has 4 divisors (see below), whose sum is σ = 21201460. Its totient is φ = 21094128.

The previous prime is 21147781. The next prime is 21147803. The reversal of 21147793 is 39774112.

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 7219969 + 13927824 = 2687^2 + 3732^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21147793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21147713) 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, 26238 + ... + 27031.

It is an arithmetic number, because the mean of its divisors is an integer number (5300365).

Almost surely, 2^21147793 is an apocalyptic number.

It is an amenable number.

21147793 is a deficient number, since it is larger than the sum of its proper divisors (53667).

21147793 is an equidigital number, since it uses as much as digits as its factorization.

21147793 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53666.

The product of its digits is 10584, while the sum is 34.

The square root of 21147793 is about 4598.6729607573. The cubic root of 21147793 is about 276.5381269317.

The spelling of 21147793 in words is "twenty-one million, one hundred forty-seven thousand, seven hundred ninety-three".