21021223120 has 20 divisors (see below), whose sum is σ = 48874343940. Its totient is φ = 8408489216.

The previous prime is 21021223087. The next prime is 21021223123. The reversal of 21021223120 is 2132212012.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 3473452096 + 17547771024 = 58936^2 + 132468^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a junction number, because it is equal to n+sod(n) for n = 21021223094 and 21021223103.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021223123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 131382565 + ... + 131382724.

It is an arithmetic number, because the mean of its divisors is an integer number (2443717197).

Almost surely, 2^21021223120 is an apocalyptic number.

21021223120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21021223120 is an abundant number, since it is smaller than the sum of its proper divisors (27853120820).

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

21021223120 is a wasteful number, since it uses less digits than its factorization.

21021223120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 262765302 (or 262765296 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 21021223120 its reverse (2132212012), we get a palindrome (23153435132).

It can be divided in two parts, 210212 and 23120, that added together give a palindrome (233332).

The spelling of 21021223120 in words is "twenty-one billion, twenty-one million, two hundred twenty-three thousand, one hundred twenty".