1664821329 has 4 divisors (see below), whose sum is σ = 2219761776. Its totient is φ = 1109880884.

The previous prime is 1664821321. The next prime is 1664821331. The reversal of 1664821329 is 9231284661.

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 a cyclic number.

It is not a de Polignac number, because 1664821329 - 2³ = 1664821321 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1664821321) 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, 277470219 + ... + 277470224.

It is an arithmetic number, because the mean of its divisors is an integer number (554940444).

Almost surely, 2^1664821329 is an apocalyptic number.

It is an amenable number.

1664821329 is a deficient number, since it is larger than the sum of its proper divisors (554940447).

1664821329 is an equidigital number, since it uses as much as digits as its factorization.

1664821329 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 554940446.

The product of its digits is 124416, while the sum is 42.

The square root of 1664821329 is about 40802.2221086058. Note that the first 3 decimals coincide. The cubic root of 1664821329 is about 1185.1933619554.

The spelling of 1664821329 in words is "one billion, six hundred sixty-four million, eight hundred twenty-one thousand, three hundred twenty-nine".