20111212111021 has 4 divisors (see below), whose sum is σ = 20154837300444. Its totient is φ = 20067586921600.

The previous prime is 20111212111013. The next prime is 20111212111033. The reversal of 20111212111021 is 12011121211102.

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 11941413253225 + 8169798857796 = 3455635^2 + 2858286^2 .

It is a cyclic number.

It is not a de Polignac number, because 20111212111021 - 2³ = 20111212111013 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20111212110986 and 20111212111004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20111215111021) 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, 21812594020 + ... + 21812594941.

It is an arithmetic number, because the mean of its divisors is an integer number (5038709325111).

Almost surely, 2^{20111212111021} is an apocalyptic number.

It is an amenable number.

20111212111021 is a deficient number, since it is larger than the sum of its proper divisors (43625189423).

20111212111021 is an equidigital number, since it uses as much as digits as its factorization.

20111212111021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43625189422.

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

Adding to 20111212111021 its reverse (12011121211102), we get a palindrome (32122333322123).

The spelling of 20111212111021 in words is "twenty trillion, one hundred eleven billion, two hundred twelve million, one hundred eleven thousand, twenty-one".