1664203021 has 8 divisors (see below), whose sum is σ = 1826034840. Its totient is φ = 1507202112.

The previous prime is 1664202949. The next prime is 1664203031. The reversal of 1664203021 is 1203024661.

It can be written as a sum of positive squares in 4 ways, for example, as 4536900 + 1659666121 = 2130^2 + 40739^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1664203021 - 2²⁵ = 1630648589 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 (1664203031) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1207006 + ... + 1208383.

It is an arithmetic number, because the mean of its divisors is an integer number (228254355).

Almost surely, 2^1664203021 is an apocalyptic number.

It is an amenable number.

1664203021 is a deficient number, since it is larger than the sum of its proper divisors (161831819).

1664203021 is a wasteful number, since it uses less digits than its factorization.

1664203021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2415455.

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 1664203021 is about 40794.6445137104. The cubic root of 1664203021 is about 1185.0466184251.

Adding to 1664203021 its reverse (1203024661), we get a palindrome (2867227682).

The spelling of 1664203021 in words is "one billion, six hundred sixty-four million, two hundred three thousand, twenty-one".