21112121221013 has 4 divisors (see below), whose sum is σ = 22354010704620. Its totient is φ = 19870231737408.

The previous prime is 21112121221007. The next prime is 21112121221033. The reversal of 21112121221013 is 31012212121112.

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 7420922394769 + 13691198826244 = 2724137^2 + 3700162^2 .

It is not a de Polignac number, because 21112121221013 - 2¹⁰ = 21112121219989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21112121221033) 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, 620944741778 + ... + 620944741811.

It is an arithmetic number, because the mean of its divisors is an integer number (5588502676155).

Almost surely, 2^{21112121221013} is an apocalyptic number.

It is an amenable number.

21112121221013 is a deficient number, since it is larger than the sum of its proper divisors (1241889483607).

21112121221013 is a wasteful number, since it uses less digits than its factorization.

21112121221013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1241889483606.

The product of its (nonzero) digits is 96, while the sum is 20.

Adding to 21112121221013 its reverse (31012212121112), we get a palindrome (52124333342125).

Subtracting 21112121221013 from its reverse (31012212121112), we obtain a palindrome (9900090900099).

The spelling of 21112121221013 in words is "twenty-one trillion, one hundred twelve billion, one hundred twenty-one million, two hundred twenty-one thousand, thirteen".