221916720 has 80 divisors (see below), whose sum is σ = 690000480. Its totient is φ = 59000832.

The previous prime is 221916707. The next prime is 221916727. The reversal of 221916720 is 27619122.

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

It is a Harshad number since it is a multiple of its sum of digits (30).

It is not an unprimeable number, because it can be changed into a prime (221916727) 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 15 ways as a sum of consecutive naturals, for example, 92172 + ... + 94548.

It is an arithmetic number, because the mean of its divisors is an integer number (8625006).

Almost surely, 2^221916720 is an apocalyptic number.

221916720 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 221916720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (345000240).

221916720 is an abundant number, since it is smaller than the sum of its proper divisors (468083760).

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

221916720 is a wasteful number, since it uses less digits than its factorization.

221916720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2782 (or 2776 counting only the distinct ones).

The product of its (nonzero) digits is 3024, while the sum is 30.

The square root of 221916720 is about 14896.8694697913. The cubic root of 221916720 is about 605.4291697945.

The spelling of 221916720 in words is "two hundred twenty-one million, nine hundred sixteen thousand, seven hundred twenty".