666814081 has 4 divisors (see below), whose sum is σ = 689807700. Its totient is φ = 643820464.

The previous prime is 666814073. The next prime is 666814117. The reversal of 666814081 is 180418666.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 382554481 + 284259600 = 19559^2 + 16860^2 .

It is a cyclic number.

It is not a de Polignac number, because 666814081 - 2³ = 666814073 is a prime.

It is a super-2 number, since 2×666814081² = 889282037239749122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (666814021) 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, 11496766 + ... + 11496823.

It is an arithmetic number, because the mean of its divisors is an integer number (172451925).

Almost surely, 2^666814081 is an apocalyptic number.

It is an amenable number.

666814081 is a deficient number, since it is larger than the sum of its proper divisors (22993619).

666814081 is a wasteful number, since it uses less digits than its factorization.

666814081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22993618.

The product of its (nonzero) digits is 55296, while the sum is 40.

The square root of 666814081 is about 25822.7434832165. The cubic root of 666814081 is about 873.6448491319.

The spelling of 666814081 in words is "six hundred sixty-six million, eight hundred fourteen thousand, eighty-one".