21099785 has 16 divisors (see below), whose sum is σ = 30460800. Its totient is φ = 13706496.

The previous prime is 21099779. The next prime is 21099811. The reversal of 21099785 is 58799012.

It is a cyclic number.

It is not a de Polignac number, because 21099785 - 2⁴ = 21099769 is a prime.

It is a Curzon 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 15 ways as a sum of consecutive naturals, for example, 15200 + ... + 16529.

It is an arithmetic number, because the mean of its divisors is an integer number (1903800).

Almost surely, 2^21099785 is an apocalyptic number.

It is an amenable number.

21099785 is a deficient number, since it is larger than the sum of its proper divisors (9361015).

21099785 is a wasteful number, since it uses less digits than its factorization.

21099785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31760.

The product of its (nonzero) digits is 45360, while the sum is 41.

The square root of 21099785 is about 4593.4502283142. The cubic root of 21099785 is about 276.3287102619.

The spelling of 21099785 in words is "twenty-one million, ninety-nine thousand, seven hundred eighty-five".