21720254244 has 48 divisors (see below), whose sum is σ = 57451692480. Its totient is φ = 6331409280.

The previous prime is 21720254209. The next prime is 21720254261. The reversal of 21720254244 is 44245202712.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3661047 + ... + 3666974.

It is an arithmetic number, because the mean of its divisors is an integer number (1196910260).

Almost surely, 2^21720254244 is an apocalyptic number.

It is an amenable number.

21720254244 is an abundant number, since it is smaller than the sum of its proper divisors (35731438236).

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

21720254244 is a wasteful number, since it uses less digits than its factorization.

21720254244 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7328060 (or 7328058 counting only the distinct ones).

The product of its (nonzero) digits is 35840, while the sum is 33.

Adding to 21720254244 its reverse (44245202712), we get a palindrome (65965456956).

The spelling of 21720254244 in words is "twenty-one billion, seven hundred twenty million, two hundred fifty-four thousand, two hundred forty-four".