21012201121 has 4 divisors (see below), whose sum is σ = 21083915412. Its totient is φ = 20940486832.

The previous prime is 21012201113. The next prime is 21012201211. The reversal of 21012201121 is 12110221012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 19554106896 + 1458094225 = 139836^2 + 38185^2 .

It is a cyclic number.

It is not a de Polignac number, because 21012201121 - 2³ = 21012201113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21012001121) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 35856706 + ... + 35857291.

It is an arithmetic number, because the mean of its divisors is an integer number (5270978853).

Almost surely, 2^21012201121 is an apocalyptic number.

It is an amenable number.

21012201121 is a deficient number, since it is larger than the sum of its proper divisors (71714291).

21012201121 is an equidigital number, since it uses as much as digits as its factorization.

21012201121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71714290.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21012201121 its reverse (12110221012), we get a palindrome (33122422133).

The spelling of 21012201121 in words is "twenty-one billion, twelve million, two hundred one thousand, one hundred twenty-one".