221211660 has 48 divisors (see below), whose sum is σ = 639378432. Its totient is φ = 57086400.

The previous prime is 221211643. The next prime is 221211673. The reversal of 221211660 is 66112122.

221211660 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, 57606 + ... + 61325.

It is an arithmetic number, because the mean of its divisors is an integer number (13320384).

Almost surely, 2^221211660 is an apocalyptic number.

221211660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221211660 is an abundant number, since it is smaller than the sum of its proper divisors (418166772).

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

221211660 is a wasteful number, since it uses less digits than its factorization.

221211660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 118974 (or 118972 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 21.

The square root of 221211660 is about 14873.1859398046. The cubic root of 221211660 is about 604.7873122566.

Adding to 221211660 its reverse (66112122), we get a palindrome (287323782).

The spelling of 221211660 in words is "two hundred twenty-one million, two hundred eleven thousand, six hundred sixty".