21793985 has 4 divisors (see below), whose sum is σ = 26152788. Its totient is φ = 17435184.

The previous prime is 21793973. The next prime is 21793987. The reversal of 21793985 is 58939712.

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 9634816 + 12159169 = 3104^2 + 3487^2 .

It is a cyclic number.

It is not a de Polignac number, because 21793985 - 2⁶ = 21793921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21793987) 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, 2179394 + ... + 2179403.

It is an arithmetic number, because the mean of its divisors is an integer number (6538197).

Almost surely, 2^21793985 is an apocalyptic number.

It is an amenable number.

21793985 is a deficient number, since it is larger than the sum of its proper divisors (4358803).

21793985 is an equidigital number, since it uses as much as digits as its factorization.

21793985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4358802.

The product of its digits is 136080, while the sum is 44.

The square root of 21793985 is about 4668.4028318045. The cubic root of 21793985 is about 279.3265490435.

The spelling of 21793985 in words is "twenty-one million, seven hundred ninety-three thousand, nine hundred eighty-five".