2181800001636 has 48 divisors (see below), whose sum is σ = 5657257103680. Its totient is φ = 727171706880.

The previous prime is 2181800001631. The next prime is 2181800001637. The reversal of 2181800001636 is 6361000081812.

2181800001636 is a `hidden beast` number, since 2 + 1 + 8 + 18 + 0 + 0 + 0 + 0 + 1 + 636 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 2181800001636.

It is not an unprimeable number, because it can be changed into a prime (2181800001631) 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, 485506 + ... + 2144601.

Almost surely, 2^{2181800001636} is an apocalyptic number.

It is an amenable number.

2181800001636 is an abundant number, since it is smaller than the sum of its proper divisors (3475457102044).

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

2181800001636 is a wasteful number, since it uses less digits than its factorization.

2181800001636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2637801 (or 2637793 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The spelling of 2181800001636 in words is "two trillion, one hundred eighty-one billion, eight hundred million, one thousand, six hundred thirty-six".