666481 has 4 divisors (see below), whose sum is σ = 684532. Its totient is φ = 648432.

The previous prime is 666467. The next prime is 666493. The reversal of 666481 is 184666.

666481 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 184666 = 2 ⋅92333.

It can be written as a sum of positive squares in 2 ways, for example, as 608400 + 58081 = 780^2 + 241^2 .

It is a cyclic number.

It is not a de Polignac number, because 666481 - 2⁷ = 666353 is a prime.

It is a super-2 number, since 2×666481² = 888393846722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (666431) 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, 8970 + ... + 9043.

It is an arithmetic number, because the mean of its divisors is an integer number (171133).

2⁶⁶⁶⁴⁸¹ is an apocalyptic number.

It is an amenable number.

666481 is a deficient number, since it is larger than the sum of its proper divisors (18051).

666481 is a wasteful number, since it uses less digits than its factorization.

666481 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18050.

The product of its digits is 6912, while the sum is 31.

The square root of 666481 is about 816.3828758616. The cubic root of 666481 is about 87.3499359820.

The spelling of 666481 in words is "six hundred sixty-six thousand, four hundred eighty-one".