81556433 has 6 divisors (see below), whose sum is σ = 94871826. Its totient is φ = 69905472.

The previous prime is 81556411. The next prime is 81556441. The reversal of 81556433 is 33465518.

It can be written as a sum of positive squares in only one way, i.e., 72454144 + 9102289 = 8512^2 + 3017^2 .

It is a de Polignac number, because none of the positive numbers 2^k-81556433 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 81556393 and 81556402.

It is not an unprimeable number, because it can be changed into a prime (81556483) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 832160 + ... + 832257.

It is an arithmetic number, because the mean of its divisors is an integer number (15811971).

Almost surely, 2^81556433 is an apocalyptic number.

It is an amenable number.

81556433 is a deficient number, since it is larger than the sum of its proper divisors (13315393).

81556433 is a wasteful number, since it uses less digits than its factorization.

81556433 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1664431 (or 1664424 counting only the distinct ones).

The product of its digits is 43200, while the sum is 35.

The square root of 81556433 is about 9030.8600365635. The cubic root of 81556433 is about 433.6633705967.

The spelling of 81556433 in words is "eighty-one million, five hundred fifty-six thousand, four hundred thirty-three".