2165800815556 has 45 divisors (see below), whose sum is σ = 4421874694349. Its totient is φ = 928138539552.

The previous prime is 2165800815517. The next prime is 2165800815613. The reversal of 2165800815556 is 6555180085612.

The square root of 2165800815556 is 1471666.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 734466140100 + 1431334675456 = 857010^2 + 1196384^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 144215760 + ... + 144230776.

Almost surely, 2^{2165800815556} is an apocalyptic number.

2165800815556 is the 1471666-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2165800815556

2165800815556 is an abundant number, since it is smaller than the sum of its proper divisors (2256073878793).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

2165800815556 is an frugal number, since it uses more digits than its factorization.

2165800815556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30066 (or 15026 counting only the distinct ones).

The product of its (nonzero) digits is 2880000, while the sum is 52.

The spelling of 2165800815556 in words is "two trillion, one hundred sixty-five billion, eight hundred million, eight hundred fifteen thousand, five hundred fifty-six".