81671633 has 4 divisors (see below), whose sum is σ = 85970160. Its totient is φ = 77373108.

The previous prime is 81671599. The next prime is 81671657. The reversal of 81671633 is 33617618.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 33617618 = 2 ⋅16808809.

It is a cyclic number.

It is not a de Polignac number, because 81671633 - 2⁸ = 81671377 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81671593 and 81671602.

It is not an unprimeable number, because it can be changed into a prime (81671683) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2149235 + ... + 2149272.

It is an arithmetic number, because the mean of its divisors is an integer number (21492540).

Almost surely, 2^81671633 is an apocalyptic number.

It is an amenable number.

81671633 is a deficient number, since it is larger than the sum of its proper divisors (4298527).

81671633 is a wasteful number, since it uses less digits than its factorization.

81671633 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4298526.

The product of its digits is 18144, while the sum is 35.

The square root of 81671633 is about 9037.2359159203. The cubic root of 81671633 is about 433.8674604303.

The spelling of 81671633 in words is "eighty-one million, six hundred seventy-one thousand, six hundred thirty-three".