221012720 has 40 divisors (see below), whose sum is σ = 517801680. Its totient is φ = 87726080.

The previous prime is 221012711. The next prime is 221012723. The reversal of 221012720 is 27210122.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221012723) 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 7 ways as a sum of consecutive naturals, for example, 65 + ... + 21024.

It is an arithmetic number, because the mean of its divisors is an integer number (12945042).

Almost surely, 2^221012720 is an apocalyptic number.

221012720 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 221012720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (258900840).

221012720 is an abundant number, since it is smaller than the sum of its proper divisors (296788960).

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

221012720 is a wasteful number, since it uses less digits than its factorization.

221012720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21233 (or 21227 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 17.

The square root of 221012720 is about 14866.4965610597. The cubic root of 221012720 is about 604.6059588361.

Adding to 221012720 its reverse (27210122), we get a palindrome (248222842).

The spelling of 221012720 in words is "two hundred twenty-one million, twelve thousand, seven hundred twenty".