81611105025 has 24 divisors (see below), whose sum is σ = 138068281120. Its totient is φ = 42513690240.

The previous prime is 81611105011. The next prime is 81611105041. The reversal of 81611105025 is 52050111618.

It is a de Polignac number, because none of the positive numbers 2^k-81611105025 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 81611104983 and 81611105001.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 12649660 + ... + 12656109.

Almost surely, 2^81611105025 is an apocalyptic number.

It is an amenable number.

81611105025 is a deficient number, since it is larger than the sum of its proper divisors (56457176095).

81611105025 is a wasteful number, since it uses less digits than its factorization.

81611105025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25305825 (or 25305820 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 30.

The spelling of 81611105025 in words is "eighty-one billion, six hundred eleven million, one hundred five thousand, twenty-five".