21985285 has 16 divisors (see below), whose sum is σ = 30240000. Its totient is φ = 15031296.

The previous prime is 21985283. The next prime is 21985291. The reversal of 21985285 is 58258912.

It is not a de Polignac number, because 21985285 - 2¹ = 21985283 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21985283) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15016 + ... + 16414.

It is an arithmetic number, because the mean of its divisors is an integer number (1890000).

Almost surely, 2^21985285 is an apocalyptic number.

It is an amenable number.

21985285 is a deficient number, since it is larger than the sum of its proper divisors (8254715).

21985285 is a wasteful number, since it uses less digits than its factorization.

21985285 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1860.

The product of its digits is 57600, while the sum is 40.

The square root of 21985285 is about 4688.8468731662. The cubic root of 21985285 is about 280.1414463912.

The spelling of 21985285 in words is "twenty-one million, nine hundred eighty-five thousand, two hundred eighty-five".