21012021011221 has 4 divisors (see below), whose sum is σ = 21072227375500. Its totient is φ = 20951814646944.

The previous prime is 21012021011213. The next prime is 21012021011239. The reversal of 21012021011221 is 12211012021012.

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 16373037342321 + 4638983668900 = 4046361^2 + 2153830^2 .

It is a cyclic number.

It is not a de Polignac number, because 21012021011221 - 2³ = 21012021011213 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21012021011195 and 21012021011204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012021011921) 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, 30103181616 + ... + 30103182313.

It is an arithmetic number, because the mean of its divisors is an integer number (5268056843875).

Almost surely, 2^{21012021011221} is an apocalyptic number.

It is an amenable number.

21012021011221 is a deficient number, since it is larger than the sum of its proper divisors (60206364279).

21012021011221 is an equidigital number, since it uses as much as digits as its factorization.

21012021011221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60206364278.

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 21012021011221 its reverse (12211012021012), we get a palindrome (33223033032233).

The spelling of 21012021011221 in words is "twenty-one trillion, twelve billion, twenty-one million, eleven thousand, two hundred twenty-one".