81945633 has 16 divisors (see below), whose sum is σ = 136221696. Its totient is φ = 42569040.

The previous prime is 81945601. The next prime is 81945649. The reversal of 81945633 is 33654918.

It is not a de Polignac number, because 81945633 - 2⁵ = 81945601 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81945591 and 81945600.

It is not an unprimeable number, because it can be changed into a prime (81945533) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 177141 + ... + 177602.

It is an arithmetic number, because the mean of its divisors is an integer number (8513856).

Almost surely, 2^81945633 is an apocalyptic number.

It is an amenable number.

81945633 is a deficient number, since it is larger than the sum of its proper divisors (54276063).

81945633 is a wasteful number, since it uses less digits than its factorization.

81945633 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 354764.

The product of its digits is 77760, while the sum is 39.

The square root of 81945633 is about 9052.3827250067. The cubic root of 81945633 is about 434.3521125425.

The spelling of 81945633 in words is "eighty-one million, nine hundred forty-five thousand, six hundred thirty-three".