2188028781 has 60 divisors (see below), whose sum is σ = 3428333172. Its totient is φ = 1389602304.

The previous prime is 2188028761. The next prime is 2188028789. The reversal of 2188028781 is 1878208812.

2188028781 is a `hidden beast` number, since 218 + 80 + 287 + 81 = 666.

2188028781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 6 ways, for example, as 242424900 + 1945603881 = 15570^2 + 44109^2 .

It is not a de Polignac number, because 2188028781 - 2⁵ = 2188028749 is a prime.

It is a super-2 number, since 2×2188028781² = 9574939892968691922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2188028789) by changing a digit.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 15970945 + ... + 15971081.

Almost surely, 2^2188028781 is an apocalyptic number.

It is an amenable number.

2188028781 is a deficient number, since it is larger than the sum of its proper divisors (1240304391).

2188028781 is an equidigital number, since it uses as much as digits as its factorization.

2188028781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332 (or 250 counting only the distinct ones).

The product of its (nonzero) digits is 114688, while the sum is 45.

The square root of 2188028781 is about 46776.3698997688. The cubic root of 2188028781 is about 1298.2281148348.

The spelling of 2188028781 in words is "two billion, one hundred eighty-eight million, twenty-eight thousand, seven hundred eighty-one".