2187218661 has 16 divisors (see below), whose sum is σ = 2940537600. Its totient is φ = 1446068160.

The previous prime is 2187218567. The next prime is 2187218669. The reversal of 2187218661 is 1668127812.

2187218661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 2187218661 - 2¹³ = 2187210469 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2187218669) 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, 197140 + ... + 207938.

It is an arithmetic number, because the mean of its divisors is an integer number (183783600).

Almost surely, 2^2187218661 is an apocalyptic number.

It is an amenable number.

2187218661 is a deficient number, since it is larger than the sum of its proper divisors (753318939).

2187218661 is a wasteful number, since it uses less digits than its factorization.

2187218661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11356.

The product of its digits is 64512, while the sum is 42.

The square root of 2187218661 is about 46767.7095975418. The cubic root of 2187218661 is about 1298.0678716064.

The spelling of 2187218661 in words is "two billion, one hundred eighty-seven million, two hundred eighteen thousand, six hundred sixty-one".