21720224242 has 16 divisors (see below), whose sum is σ = 33346162080. Its totient is φ = 10604960352.

The previous prime is 21720224177. The next prime is 21720224249. The reversal of 21720224242 is 24242202712.

It is a super-2 number, since 2×21720224242² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21720224242.

It is not an unprimeable number, because it can be changed into a prime (21720224249) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 350533 + ... + 407815.

It is an arithmetic number, because the mean of its divisors is an integer number (2084135130).

Almost surely, 2^21720224242 is an apocalyptic number.

21720224242 is a deficient number, since it is larger than the sum of its proper divisors (11625937838).

21720224242 is a wasteful number, since it uses less digits than its factorization.

21720224242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61737.

The product of its (nonzero) digits is 7168, while the sum is 28.

Adding to 21720224242 its reverse (24242202712), we get a palindrome (45962426954).

The spelling of 21720224242 in words is "twenty-one billion, seven hundred twenty million, two hundred twenty-four thousand, two hundred forty-two".