21816793 has 4 divisors (see below), whose sum is σ = 21843940. Its totient is φ = 21789648.

The previous prime is 21816757. The next prime is 21816803. The reversal of 21816793 is 39761812.

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 13307904 + 8508889 = 3648^2 + 2917^2 .

It is a cyclic number.

It is not a de Polignac number, because 21816793 - 2¹⁷ = 21685721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21816703) 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, 12330 + ... + 13987.

It is an arithmetic number, because the mean of its divisors is an integer number (5460985).

Almost surely, 2^21816793 is an apocalyptic number.

It is an amenable number.

21816793 is a deficient number, since it is larger than the sum of its proper divisors (27147).

21816793 is an equidigital number, since it uses as much as digits as its factorization.

21816793 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27146.

The product of its digits is 18144, while the sum is 37.

The square root of 21816793 is about 4670.8449984987. The cubic root of 21816793 is about 279.4239560236.

The spelling of 21816793 in words is "twenty-one million, eight hundred sixteen thousand, seven hundred ninety-three".