81990073 has 8 divisors (see below), whose sum is σ = 94151520. Its totient is φ = 70613280.

The previous prime is 81990059. The next prime is 81990089. The reversal of 81990073 is 37009918.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81990073 is a prime.

It is a super-3 number, since 3×81990073³ (a number of 25 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81990373) 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 7 ways as a sum of consecutive naturals, for example, 195940 + ... + 196357.

It is an arithmetic number, because the mean of its divisors is an integer number (11768940).

Almost surely, 2^81990073 is an apocalyptic number.

It is an amenable number.

81990073 is a deficient number, since it is larger than the sum of its proper divisors (12161447).

81990073 is a wasteful number, since it uses less digits than its factorization.

81990073 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 392327.

The product of its (nonzero) digits is 13608, while the sum is 37.

The square root of 81990073 is about 9054.8369946675. The cubic root of 81990073 is about 434.4306162971.

The spelling of 81990073 in words is "eighty-one million, nine hundred ninety thousand, seventy-three".