21120221021 has 8 divisors (see below), whose sum is σ = 21236139384. Its totient is φ = 21004369920.

The previous prime is 21120221011. The next prime is 21120221027. The reversal of 21120221021 is 12012202112.

It can be written as a sum of positive squares in 4 ways, for example, as 1065696025 + 20054524996 = 32645^2 + 141614^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21120221021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21120220987 and 21120221005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21120221027) 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, 694781 + ... + 724541.

It is an arithmetic number, because the mean of its divisors is an integer number (2654517423).

Almost surely, 2^21120221021 is an apocalyptic number.

It is an amenable number.

21120221021 is a deficient number, since it is larger than the sum of its proper divisors (115918363).

21120221021 is a wasteful number, since it uses less digits than its factorization.

21120221021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33631.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21120221021 its reverse (12012202112), we get a palindrome (33132423133).

The spelling of 21120221021 in words is "twenty-one billion, one hundred twenty million, two hundred twenty-one thousand, twenty-one".