21884985 has 20 divisors (see below), whose sum is σ = 39231588. Its totient is φ = 11671776.

The previous prime is 21884981. The next prime is 21884987. The reversal of 21884985 is 58948812.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 15397776 + 6487209 = 3924^2 + 2547^2 .

It is not a de Polignac number, because 21884985 - 2² = 21884981 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 21884985.

It is not an unprimeable number, because it can be changed into a prime (21884981) by changing a digit.

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 19 ways as a sum of consecutive naturals, for example, 26614 + ... + 27423.

Almost surely, 2^21884985 is an apocalyptic number.

It is an amenable number.

21884985 is a deficient number, since it is larger than the sum of its proper divisors (17346603).

21884985 is an equidigital number, since it uses as much as digits as its factorization.

21884985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54054 (or 54045 counting only the distinct ones).

The product of its digits is 184320, while the sum is 45.

The square root of 21884985 is about 4678.1390530851. The cubic root of 21884985 is about 279.7147818440.

The spelling of 21884985 in words is "twenty-one million, eight hundred eighty-four thousand, nine hundred eighty-five".