221612066 has 12 divisors (see below), whose sum is σ = 359956242. Its totient is φ = 102282336.

The previous prime is 221612063. The next prime is 221612077. The reversal of 221612066 is 660216122.

It can be written as a sum of positive squares in 3 ways, for example, as 35153041 + 186459025 = 5929^2 + 13655^2 .

It is a super-2 number, since 2×221612066² = 98223815593576712, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (26).

It is not an unprimeable number, because it can be changed into a prime (221612063) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 327491 + ... + 328166.

Almost surely, 2^221612066 is an apocalyptic number.

221612066 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

221612066 is a deficient number, since it is larger than the sum of its proper divisors (138344176).

221612066 is a wasteful number, since it uses less digits than its factorization.

221612066 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 655685 (or 655672 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 26.

The square root of 221612066 is about 14886.6405209503. The cubic root of 221612066 is about 605.1519924112.

Adding to 221612066 its reverse (660216122), we get a palindrome (881828188).

The spelling of 221612066 in words is "two hundred twenty-one million, six hundred twelve thousand, sixty-six".