2181815999 has 16 divisors (see below), whose sum is σ = 2558753280. Its totient is φ = 1839087360.

The previous prime is 2181815981. The next prime is 2181816017. The reversal of 2181815999 is 9995181812.

It is an interprime number because it is at equal distance from previous prime (2181815981) and next prime (2181816017).

It is not a de Polignac number, because 2181815999 - 2¹⁶ = 2181750463 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 2181815999.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2181815099) 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, 101234 + ... + 120879.

It is an arithmetic number, because the mean of its divisors is an integer number (159922080).

Almost surely, 2^2181815999 is an apocalyptic number.

2181815999 is a deficient number, since it is larger than the sum of its proper divisors (376937281).

2181815999 is a wasteful number, since it uses less digits than its factorization.

2181815999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 222190.

The product of its digits is 466560, while the sum is 53.

The square root of 2181815999 is about 46709.9132840128. The cubic root of 2181815999 is about 1296.9982019649.

The spelling of 2181815999 in words is "two billion, one hundred eighty-one million, eight hundred fifteen thousand, nine hundred ninety-nine".