81989807 has 8 divisors (see below), whose sum is σ = 87346560. Its totient is φ = 76737240.

The previous prime is 81989801. The next prime is 81989821. The reversal of 81989807 is 70898918.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 81989807 - 2¹⁰ = 81988783 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81989801) 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, 24419 + ... + 27572.

It is an arithmetic number, because the mean of its divisors is an integer number (10918320).

Almost surely, 2^81989807 is an apocalyptic number.

81989807 is a deficient number, since it is larger than the sum of its proper divisors (5356753).

81989807 is a wasteful number, since it uses less digits than its factorization.

81989807 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52093.

The product of its (nonzero) digits is 290304, while the sum is 50.

The square root of 81989807 is about 9054.8223063735. The cubic root of 81989807 is about 434.4301464895.

The spelling of 81989807 in words is "eighty-one million, nine hundred eighty-nine thousand, eight hundred seven".