21827985 has 8 divisors (see below), whose sum is σ = 34924800. Its totient is φ = 11641584.

The previous prime is 21827977. The next prime is 21828029. The reversal of 21827985 is 58972812.

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

It is not a de Polignac number, because 21827985 - 2³ = 21827977 is a prime.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 727585 + ... + 727614.

It is an arithmetic number, because the mean of its divisors is an integer number (4365600).

Almost surely, 2^21827985 is an apocalyptic number.

It is an amenable number.

21827985 is a deficient number, since it is larger than the sum of its proper divisors (13096815).

21827985 is a wasteful number, since it uses less digits than its factorization.

21827985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1455207.

The product of its digits is 80640, while the sum is 42.

The square root of 21827985 is about 4672.0429150426. The cubic root of 21827985 is about 279.4717292886.

It can be divided in two parts, 218 and 27985, that added together give a triangular number (28203 = T₂₃₇).

The spelling of 21827985 in words is "twenty-one million, eight hundred twenty-seven thousand, nine hundred eighty-five".