21220320121 has 16 divisors (see below), whose sum is σ = 28491619968. Its totient is φ = 15263366400.

The previous prime is 21220320109. The next prime is 21220320151. The reversal of 21220320121 is 12102302212.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21220320121 - 2⁵ = 21220320089 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21220320095 and 21220320104.

It is not an unprimeable number, because it can be changed into a prime (21220320151) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10598560 + ... + 10600561.

It is an arithmetic number, because the mean of its divisors is an integer number (1780726248).

Almost surely, 2^21220320121 is an apocalyptic number.

It is an amenable number.

21220320121 is a deficient number, since it is larger than the sum of its proper divisors (7271299847).

21220320121 is a wasteful number, since it uses less digits than its factorization.

21220320121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21199152.

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

Adding to 21220320121 its reverse (12102302212), we get a palindrome (33322622333).

It can be divided in two parts, 212203 and 20121, that added together give a square (232324 = 482²).

The spelling of 21220320121 in words is "twenty-one billion, two hundred twenty million, three hundred twenty thousand, one hundred twenty-one".