21755985 has 8 divisors (see below), whose sum is σ = 34809600. Its totient is φ = 11603184.

The previous prime is 21755959. The next prime is 21756041. The reversal of 21755985 is 58955712.

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

It is not a de Polignac number, because 21755985 - 2¹⁰ = 21754961 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 725185 + ... + 725214.

It is an arithmetic number, because the mean of its divisors is an integer number (4351200).

Almost surely, 2^21755985 is an apocalyptic number.

It is an amenable number.

21755985 is a deficient number, since it is larger than the sum of its proper divisors (13053615).

21755985 is a wasteful number, since it uses less digits than its factorization.

21755985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1450407.

The product of its digits is 126000, while the sum is 42.

The square root of 21755985 is about 4664.3311417608. The cubic root of 21755985 is about 279.1641099739.

The spelling of 21755985 in words is "twenty-one million, seven hundred fifty-five thousand, nine hundred eighty-five".