2205721836 has 18 divisors (see below), whose sum is σ = 5575574732. Its totient is φ = 735240600.

The previous prime is 2205721823. The next prime is 2205721853. The reversal of 2205721836 is 6381275022.

2205721836 is a `hidden beast` number, since 2 + 2 + 0 + 572 + 1 + 83 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 61270051 = 2205721836 / (2 + 2 + 0 + 5 + 7 + 2 + 1 + 8 + 3 + 6).

It is a self number, because there is not a number n which added to its sum of digits gives 2205721836.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 30634990 + ... + 30635061.

Almost surely, 2^2205721836 is an apocalyptic number.

It is an amenable number.

2205721836 is an abundant number, since it is smaller than the sum of its proper divisors (3369852896).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

2205721836 is a wasteful number, since it uses less digits than its factorization.

2205721836 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61270061 (or 61270056 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 36.

The square root of 2205721836 is about 46965.1129669673. The cubic root of 2205721836 is about 1301.7180118003.

Adding to 2205721836 its reverse (6381275022), we get a palindrome (8586996858).

The spelling of 2205721836 in words is "two billion, two hundred five million, seven hundred twenty-one thousand, eight hundred thirty-six".