1664824397 has 4 divisors (see below), whose sum is σ = 1665096480. Its totient is φ = 1664552316.

The previous prime is 1664824391. The next prime is 1664824423. The reversal of 1664824397 is 7934284661.

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 1664824397 - 2²⁶ = 1597715533 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1664824391) 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, 126647 + ... + 139172.

It is an arithmetic number, because the mean of its divisors is an integer number (416274120).

Almost surely, 2^1664824397 is an apocalyptic number.

It is an amenable number.

1664824397 is a deficient number, since it is larger than the sum of its proper divisors (272083).

1664824397 is an equidigital number, since it uses as much as digits as its factorization.

1664824397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 272082.

The product of its digits is 1741824, while the sum is 50.

The square root of 1664824397 is about 40802.2597045801. The cubic root of 1664824397 is about 1185.1940899957.

The spelling of 1664824397 in words is "one billion, six hundred sixty-four million, eight hundred twenty-four thousand, three hundred ninety-seven".