2166555043251 has 24 divisors (see below), whose sum is σ = 3180998236416. Its totient is φ = 1420590407040.

The previous prime is 2166555043241. The next prime is 2166555043259. The reversal of 2166555043251 is 1523405556612.

2166555043251 is a `hidden beast` number, since 2 + 1 + 6 + 6 + 5 + 550 + 43 + 2 + 51 = 666.

It is a de Polignac number, because none of the positive numbers 2^k-2166555043251 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 2166555043197 and 2166555043206.

It is not an unprimeable number, because it can be changed into a prime (2166555043259) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7982391 + ... + 8249343.

It is an arithmetic number, because the mean of its divisors is an integer number (132541593184).

Almost surely, 2^{2166555043251} is an apocalyptic number.

2166555043251 is a deficient number, since it is larger than the sum of its proper divisors (1014443193165).

2166555043251 is a wasteful number, since it uses less digits than its factorization.

2166555043251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 281803 (or 281800 counting only the distinct ones).

The product of its (nonzero) digits is 1080000, while the sum is 45.

The spelling of 2166555043251 in words is "two trillion, one hundred sixty-six billion, five hundred fifty-five million, forty-three thousand, two hundred fifty-one".