2181856529 has 2 divisors, whose sum is σ = 2181856530. Its totient is φ = 2181856528.

The previous prime is 2181856487. The next prime is 2181856543. The reversal of 2181856529 is 9256581812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2059798225 + 122058304 = 45385^2 + 11048^2 .

It is a cyclic number.

It is not a de Polignac number, because 2181856529 - 2²⁰ = 2180807953 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not a weakly prime, because it can be changed into another prime (2181852529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1090928264 + 1090928265.

It is an arithmetic number, because the mean of its divisors is an integer number (1090928265).

Almost surely, 2^2181856529 is an apocalyptic number.

It is an amenable number.

2181856529 is a deficient number, since it is larger than the sum of its proper divisors (1).

2181856529 is an equidigital number, since it uses as much as digits as its factorization.

2181856529 is an evil number, because the sum of its binary digits is even.

The product of its digits is 345600, while the sum is 47.

The square root of 2181856529 is about 46710.3471299454. The cubic root of 2181856529 is about 1297.0062330441.

The spelling of 2181856529 in words is "two billion, one hundred eighty-one million, eight hundred fifty-six thousand, five hundred twenty-nine".