21221040121 has 2 divisors, whose sum is σ = 21221040122. Its totient is φ = 21221040120.

The previous prime is 21221040107. The next prime is 21221040161. The reversal of 21221040121 is 12104012212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18333160000 + 2887880121 = 135400^2 + 53739^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221040121 - 2¹¹ = 21221038073 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21221040095 and 21221040104.

It is not a weakly prime, because it can be changed into another prime (21221040101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610520060 + 10610520061.

It is an arithmetic number, because the mean of its divisors is an integer number (10610520061).

Almost surely, 2^21221040121 is an apocalyptic number.

It is an amenable number.

21221040121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221040121 is an equidigital number, since it uses as much as digits as its factorization.

21221040121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21221040121 its reverse (12104012212), we get a palindrome (33325052333).

The spelling of 21221040121 in words is "twenty-one billion, two hundred twenty-one million, forty thousand, one hundred twenty-one".