66810081 has 16 divisors (see below), whose sum is σ = 96445440. Its totient is φ = 40894080.

The previous prime is 66810047. The next prime is 66810083. The reversal of 66810081 is 18001866.

It is not a de Polignac number, because 66810081 - 2⁹ = 66809569 is a prime.

It is a super-2 number, since 2×66810081² = 8927173846453122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (66810083) 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, 2965 + ... + 11933.

It is an arithmetic number, because the mean of its divisors is an integer number (6027840).

Almost surely, 2^66810081 is an apocalyptic number.

It is an amenable number.

66810081 is a deficient number, since it is larger than the sum of its proper divisors (29635359).

66810081 is a wasteful number, since it uses less digits than its factorization.

66810081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9176.

The product of its (nonzero) digits is 2304, while the sum is 30.

The square root of 66810081 is about 8173.7433896594. The cubic root of 66810081 is about 405.7706831073.

The spelling of 66810081 in words is "sixty-six million, eight hundred ten thousand, eighty-one".