21930785 has 8 divisors (see below), whose sum is σ = 26358696. Its totient is φ = 17516800.

The previous prime is 21930743. The next prime is 21930791. The reversal of 21930785 is 58703912.

It can be written as a sum of positive squares in 4 ways, for example, as 12737761 + 9193024 = 3569^2 + 3032^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21930785 - 2⁶ = 21930721 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 377 + ... + 6633.

It is an arithmetic number, because the mean of its divisors is an integer number (3294837).

Almost surely, 2^21930785 is an apocalyptic number.

It is an amenable number.

21930785 is a deficient number, since it is larger than the sum of its proper divisors (4427911).

21930785 is an equidigital number, since it uses as much as digits as its factorization.

21930785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6963.

The product of its (nonzero) digits is 15120, while the sum is 35.

The square root of 21930785 is about 4683.0316035662. The cubic root of 21930785 is about 279.9097710973.

The spelling of 21930785 in words is "twenty-one million, nine hundred thirty thousand, seven hundred eighty-five".