1664221205 has 16 divisors (see below), whose sum is σ = 2182754304. Its totient is φ = 1212637440.

The previous prime is 1664221199. The next prime is 1664221213. The reversal of 1664221205 is 5021224661.

It is not a de Polignac number, because 1664221205 - 2¹² = 1664217109 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 313157 + ... + 318426.

It is an arithmetic number, because the mean of its divisors is an integer number (136422144).

Almost surely, 2^1664221205 is an apocalyptic number.

It is an amenable number.

1664221205 is a deficient number, since it is larger than the sum of its proper divisors (518533099).

1664221205 is a wasteful number, since it uses less digits than its factorization.

1664221205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 631636.

The product of its (nonzero) digits is 5760, while the sum is 29.

The square root of 1664221205 is about 40794.8673854935. The cubic root of 1664221205 is about 1185.0509345670.

Adding to 1664221205 its reverse (5021224661), we get a palindrome (6685445866).

The spelling of 1664221205 in words is "one billion, six hundred sixty-four million, two hundred twenty-one thousand, two hundred five".