221406640 has 160 divisors (see below), whose sum is σ = 671207040. Its totient is φ = 65912832.

The previous prime is 221406629. The next prime is 221406643. The reversal of 221406640 is 46604122.

It is not an unprimeable number, because it can be changed into a prime (221406643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 122866 + ... + 124654.

It is an arithmetic number, because the mean of its divisors is an integer number (4195044).

Almost surely, 2^221406640 is an apocalyptic number.

221406640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221406640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (335603520).

221406640 is an abundant number, since it is smaller than the sum of its proper divisors (449800400).

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

221406640 is a wasteful number, since it uses less digits than its factorization.

221406640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1839 (or 1833 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 25.

The square root of 221406640 is about 14879.7392450271. The cubic root of 221406640 is about 604.9649502724.

The spelling of 221406640 in words is "two hundred twenty-one million, four hundred six thousand, six hundred forty".