2181856564 has 36 divisors (see below), whose sum is σ = 4036771200. Its totient is φ = 1031720976.

The previous prime is 2181856553. The next prime is 2181856591. The reversal of 2181856564 is 4656581812.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1239517 + ... + 1241275.

Almost surely, 2^2181856564 is an apocalyptic number.

It is an amenable number.

2181856564 is a deficient number, since it is larger than the sum of its proper divisors (1854914636).

2181856564 is a wasteful number, since it uses less digits than its factorization.

2181856564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2660 (or 2639 counting only the distinct ones).

The product of its digits is 460800, while the sum is 46.

The square root of 2181856564 is about 46710.3475045947. The cubic root of 2181856564 is about 1297.0062399794.

The spelling of 2181856564 in words is "two billion, one hundred eighty-one million, eight hundred fifty-six thousand, five hundred sixty-four".