25821778161 has 16 divisors (see below), whose sum is σ = 35929687680. Its totient is φ = 16464349440.

The previous prime is 25821778141. The next prime is 25821778187. The reversal of 25821778161 is 16187712852.

It is not a de Polignac number, because 25821778161 - 2⁷ = 25821778033 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 25821778161.

It is not an unprimeable number, because it can be changed into a prime (25821778141) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 1189081 + ... + 1210601.

It is an arithmetic number, because the mean of its divisors is an integer number (2245605480).

Almost surely, 2^25821778161 is an apocalyptic number.

It is an amenable number.

25821778161 is a deficient number, since it is larger than the sum of its proper divisors (10107909519).

25821778161 is a wasteful number, since it uses less digits than its factorization.

25821778161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38936.

The product of its digits is 376320, while the sum is 48.

The spelling of 25821778161 in words is "twenty-five billion, eight hundred twenty-one million, seven hundred seventy-eight thousand, one hundred sixty-one".