1664478081 has 24 divisors (see below), whose sum is σ = 2774925504. Its totient is φ = 941709600.

The previous prime is 1664478077. The next prime is 1664478083. The reversal of 1664478081 is 1808744661.

1664478081 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 1664478081 - 2² = 1664478077 is a prime.

It is a super-2 number, since 2×1664478081² = 5540974564258885122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1664478083) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 124431 + ... + 137156.

It is an arithmetic number, because the mean of its divisors is an integer number (115621896).

Almost surely, 2^1664478081 is an apocalyptic number.

It is an amenable number.

1664478081 is a deficient number, since it is larger than the sum of its proper divisors (1110447423).

1664478081 is a wasteful number, since it uses less digits than its factorization.

1664478081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 261701 (or 261698 counting only the distinct ones).

The product of its (nonzero) digits is 258048, while the sum is 45.

The square root of 1664478081 is about 40798.0156502740. The cubic root of 1664478081 is about 1185.1119031214. Note that the first 3 decimals are identical.

The spelling of 1664478081 in words is "one billion, six hundred sixty-four million, four hundred seventy-eight thousand, eighty-one".