21120021012221 has 4 divisors (see below), whose sum is σ = 21121443154944. Its totient is φ = 21118598869500.

The previous prime is 21120021012193. The next prime is 21120021012229. The reversal of 21120021012221 is 12221012002112.

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 not a de Polignac number, because 21120021012221 - 2⁴² = 16721974501117 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21120021012221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21120021012229) 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, 711049085 + ... + 711078786.

It is an arithmetic number, because the mean of its divisors is an integer number (5280360788736).

Almost surely, 2^{21120021012221} is an apocalyptic number.

It is an amenable number.

21120021012221 is a deficient number, since it is larger than the sum of its proper divisors (1422142723).

21120021012221 is a wasteful number, since it uses less digits than its factorization.

21120021012221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1422142722.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 21120021012221 its reverse (12221012002112), we get a palindrome (33341033014333).

The spelling of 21120021012221 in words is "twenty-one trillion, one hundred twenty billion, twenty-one million, twelve thousand, two hundred twenty-one".