2181861555 has 8 divisors (see below), whose sum is σ = 3490978512. Its totient is φ = 1163659488.

The previous prime is 2181861553. The next prime is 2181861559. The reversal of 2181861555 is 5551681812.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 2181861555 - 2¹ = 2181861553 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2181861551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 72728704 + ... + 72728733.

It is an arithmetic number, because the mean of its divisors is an integer number (436372314).

Almost surely, 2^2181861555 is an apocalyptic number.

2181861555 is a deficient number, since it is larger than the sum of its proper divisors (1309116957).

2181861555 is a wasteful number, since it uses less digits than its factorization.

2181861555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145457445.

The product of its digits is 96000, while the sum is 42.

The square root of 2181861555 is about 46710.4009295574. The cubic root of 2181861555 is about 1297.0072289465.

The spelling of 2181861555 in words is "two billion, one hundred eighty-one million, eight hundred sixty-one thousand, five hundred fifty-five".