21618793 has 4 divisors (see below), whose sum is σ = 24707200. Its totient is φ = 18530388.

The previous prime is 21618787. The next prime is 21618803. The reversal of 21618793 is 39781612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21618793 - 2⁹ = 21618281 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21618703) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1544193 + ... + 1544206.

It is an arithmetic number, because the mean of its divisors is an integer number (6176800).

Almost surely, 2^21618793 is an apocalyptic number.

It is an amenable number.

21618793 is a deficient number, since it is larger than the sum of its proper divisors (3088407).

21618793 is an equidigital number, since it uses as much as digits as its factorization.

21618793 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3088406.

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

The square root of 21618793 is about 4649.6013807637. The cubic root of 21618793 is about 278.5760745476.

The spelling of 21618793 in words is "twenty-one million, six hundred eighteen thousand, seven hundred ninety-three".