21609084285 has 128 divisors (see below), whose sum is σ = 43128115200. Its totient is φ = 10212065280.

The previous prime is 21609084281. The next prime is 21609084307. The reversal of 21609084285 is 58248090612.

21609084285 is a `hidden beast` number, since 216 + 0 + 9 + 0 + 8 + 428 + 5 = 666.

It is not a de Polignac number, because 21609084285 - 2² = 21609084281 is a prime.

It is a super-2 number, since 2×21609084285² (a number of 21 digits) contains 22 as substring.

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

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21609084285.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21609084281) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 2628261 + ... + 2636469.

It is an arithmetic number, because the mean of its divisors is an integer number (336938400).

Almost surely, 2^21609084285 is an apocalyptic number.

It is an amenable number.

21609084285 is a deficient number, since it is larger than the sum of its proper divisors (21519030915).

21609084285 is a wasteful number, since it uses less digits than its factorization.

21609084285 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8308 (or 8302 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 45.

The spelling of 21609084285 in words is "twenty-one billion, six hundred nine million, eighty-four thousand, two hundred eighty-five".