21221201211121 has 4 divisors (see below), whose sum is σ = 21305747829744. Its totient is φ = 21136654592500.

The previous prime is 21221201211101. The next prime is 21221201211127. The reversal of 21221201211121 is 12111210212212.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21221201211121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21221201211127) 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, 42273308935 + ... + 42273309436.

It is an arithmetic number, because the mean of its divisors is an integer number (5326436957436).

Almost surely, 2^{21221201211121} is an apocalyptic number.

It is an amenable number.

21221201211121 is a deficient number, since it is larger than the sum of its proper divisors (84546618623).

21221201211121 is an equidigital number, since it uses as much as digits as its factorization.

21221201211121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84546618622.

The product of its (nonzero) digits is 64, while the sum is 19.

Adding to 21221201211121 its reverse (12111210212212), we get a palindrome (33332411423333).

The spelling of 21221201211121 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred one million, two hundred eleven thousand, one hundred twenty-one".