221668720 has 80 divisors (see below), whose sum is σ = 634334400. Its totient is φ = 70152192.

The previous prime is 221668703. The next prime is 221668747. The reversal of 221668720 is 27866122.

221668720 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (80).

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, 7945 + ... + 22504.

It is an arithmetic number, because the mean of its divisors is an integer number (7929180).

Almost surely, 2^221668720 is an apocalyptic number.

221668720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221668720 is an abundant number, since it is smaller than the sum of its proper divisors (412665680).

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

221668720 is a wasteful number, since it uses less digits than its factorization.

221668720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30482 (or 30476 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 34.

The square root of 221668720 is about 14888.5432464026. The cubic root of 221668720 is about 605.2035560294.

The spelling of 221668720 in words is "two hundred twenty-one million, six hundred sixty-eight thousand, seven hundred twenty".