666802481 has 4 divisors (see below), whose sum is σ = 689795700. Its totient is φ = 643809264.

The previous prime is 666802471. The next prime is 666802523. The reversal of 666802481 is 184208666.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 184208666 = 2 ⋅92104333.

It can be written as a sum of positive squares in 2 ways, for example, as 212430625 + 454371856 = 14575^2 + 21316^2 .

It is a cyclic number.

It is not a de Polignac number, because 666802481 - 2¹⁸ = 666540337 is a prime.

It is a super-2 number, since 2×666802481² = 889251097335510722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (666802421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11496566 + ... + 11496623.

It is an arithmetic number, because the mean of its divisors is an integer number (172448925).

Almost surely, 2^666802481 is an apocalyptic number.

It is an amenable number.

666802481 is a deficient number, since it is larger than the sum of its proper divisors (22993219).

666802481 is a wasteful number, since it uses less digits than its factorization.

666802481 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22993218.

The product of its (nonzero) digits is 110592, while the sum is 41.

The square root of 666802481 is about 25822.5188740371. The cubic root of 666802481 is about 873.6397830826.

The spelling of 666802481 in words is "six hundred sixty-six million, eight hundred two thousand, four hundred eighty-one".