2187428581 has 4 divisors (see below), whose sum is σ = 2355692332. Its totient is φ = 2019164832.

The previous prime is 2187428543. The next prime is 2187428591. The reversal of 2187428581 is 1858247812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 915365025 + 1272063556 = 30255^2 + 35666^2 .

It is a cyclic number.

It is not a de Polignac number, because 2187428581 - 2¹⁷ = 2187297509 is a prime.

It is a super-2 number, since 2×2187428581² = 9569687593951347122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2187428531) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 84131856 + ... + 84131881.

It is an arithmetic number, because the mean of its divisors is an integer number (588923083).

Almost surely, 2^2187428581 is an apocalyptic number.

It is an amenable number.

2187428581 is a deficient number, since it is larger than the sum of its proper divisors (168263751).

2187428581 is a wasteful number, since it uses less digits than its factorization.

2187428581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 168263750.

The product of its digits is 286720, while the sum is 46.

The square root of 2187428581 is about 46769.9538272169. The cubic root of 2187428581 is about 1298.1093979667.

The spelling of 2187428581 in words is "two billion, one hundred eighty-seven million, four hundred twenty-eight thousand, five hundred eighty-one".