664193081 has 4 divisors (see below), whose sum is σ = 664453200. Its totient is φ = 663932964.

The previous prime is 664193039. The next prime is 664193083. The reversal of 664193081 is 180391466.

664193081 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 a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 180391466 = 2 ⋅90195733.

It is a cyclic number.

It is not a de Polignac number, because 664193081 - 2¹⁴ = 664176697 is a prime.

It is a super-2 number, since 2×664193081² = 882304897696545122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (664193083) 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, 126191 + ... + 131348.

It is an arithmetic number, because the mean of its divisors is an integer number (166113300).

Almost surely, 2^664193081 is an apocalyptic number.

It is an amenable number.

664193081 is a deficient number, since it is larger than the sum of its proper divisors (260119).

664193081 is a wasteful number, since it uses less digits than its factorization.

664193081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 260118.

The product of its (nonzero) digits is 31104, while the sum is 38.

The square root of 664193081 is about 25771.9436791252. The cubic root of 664193081 is about 872.4986876388.

The spelling of 664193081 in words is "six hundred sixty-four million, one hundred ninety-three thousand, eighty-one".