1665221110 has 64 divisors (see below), whose sum is σ = 3567919104. Its totient is φ = 547545600.

The previous prime is 1665221087. The next prime is 1665221113. The reversal of 1665221110 is 111225661.

It is a happy number.

It is a super-2 number, since 2×1665221110² = 5545922690379264200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665221113) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 241815 + ... + 248605.

It is an arithmetic number, because the mean of its divisors is an integer number (55748736).

Almost surely, 2^1665221110 is an apocalyptic number.

1665221110 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1665221110 is an abundant number, since it is smaller than the sum of its proper divisors (1902697994).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1665221110 is a wasteful number, since it uses less digits than its factorization.

1665221110 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6949.

The product of its (nonzero) digits is 720, while the sum is 25.

The square root of 1665221110 is about 40807.1208246796. The cubic root of 1665221110 is about 1185.2882229589.

Adding to 1665221110 its reverse (111225661), we get a palindrome (1776446771).

The spelling of 1665221110 in words is "one billion, six hundred sixty-five million, two hundred twenty-one thousand, one hundred ten".