21223251072 has 128 divisors (see below), whose sum is σ = 62854848000. Its totient is φ = 7049935872.

The previous prime is 21223251067. The next prime is 21223251079. The reversal of 21223251072 is 27015232212.

It is a tau number, because it is divible by the number of its divisors (128).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21223251079) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1002129 + ... + 1023087.

It is an arithmetic number, because the mean of its divisors is an integer number (491053500).

Almost surely, 2^21223251072 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21223251072, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31427424000).

21223251072 is an abundant number, since it is smaller than the sum of its proper divisors (41631596928).

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

21223251072 is a wasteful number, since it uses less digits than its factorization.

21223251072 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21275 (or 21257 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 27.

Adding to 21223251072 its reverse (27015232212), we get a palindrome (48238483284).

The spelling of 21223251072 in words is "twenty-one billion, two hundred twenty-three million, two hundred fifty-one thousand, seventy-two".