664540181 has 4 divisors (see below), whose sum is σ = 699516000. Its totient is φ = 629564364.

The previous prime is 664540169. The next prime is 664540193. The reversal of 664540181 is 181045466.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (664540169) and next prime (664540193).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-664540181 is a prime.

It is a super-2 number, since 2×664540181² = 883227304327025522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664540111) 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 3 ways as a sum of consecutive naturals, for example, 17487881 + ... + 17487918.

It is an arithmetic number, because the mean of its divisors is an integer number (174879000).

Almost surely, 2^664540181 is an apocalyptic number.

It is an amenable number.

664540181 is a deficient number, since it is larger than the sum of its proper divisors (34975819).

664540181 is a wasteful number, since it uses less digits than its factorization.

664540181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34975818.

The product of its (nonzero) digits is 23040, while the sum is 35.

The square root of 664540181 is about 25778.6768667440. The cubic root of 664540181 is about 872.6506472442.

The spelling of 664540181 in words is "six hundred sixty-four million, five hundred forty thousand, one hundred eighty-one".