221220424 has 8 divisors (see below), whose sum is σ = 414788310. Its totient is φ = 110610208.

The previous prime is 221220403. The next prime is 221220427. The reversal of 221220424 is 424022122.

221220424 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 209728324 + 11492100 = 14482^2 + 3390^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (221220427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 13826269 + ... + 13826284.

Almost surely, 2^221220424 is an apocalyptic number.

It is an amenable number.

221220424 is a deficient number, since it is larger than the sum of its proper divisors (193567886).

221220424 is a wasteful number, since it uses less digits than its factorization.

221220424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27652559 (or 27652555 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 19.

The square root of 221220424 is about 14873.4805610523. The cubic root of 221220424 is about 604.7952990056.

Adding to 221220424 its reverse (424022122), we get a palindrome (645242546).

The spelling of 221220424 in words is "two hundred twenty-one million, two hundred twenty thousand, four hundred twenty-four".