1664189947 has 4 divisors (see below), whose sum is σ = 1901931376. Its totient is φ = 1426448520.

The previous prime is 1664189921. The next prime is 1664189953. The reversal of 1664189947 is 7499814661.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 1664189947 - 2¹⁵ = 1664157179 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1664189047) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 118870704 + ... + 118870717.

It is an arithmetic number, because the mean of its divisors is an integer number (475482844).

Almost surely, 2^1664189947 is an apocalyptic number.

1664189947 is a deficient number, since it is larger than the sum of its proper divisors (237741429).

1664189947 is an equidigital number, since it uses as much as digits as its factorization.

1664189947 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 237741428.

The product of its digits is 2612736, while the sum is 55.

The square root of 1664189947 is about 40794.4842717738. The cubic root of 1664189947 is about 1185.0435151699.

The spelling of 1664189947 in words is "one billion, six hundred sixty-four million, one hundred eighty-nine thousand, nine hundred forty-seven".