21012020211021 has 16 divisors (see below), whose sum is σ = 32018697904128. Its totient is φ = 12006725670000.

The previous prime is 21012020211019. The next prime is 21012020211047. The reversal of 21012020211021 is 12011202021012.

It is not a de Polignac number, because 21012020211021 - 2¹ = 21012020211019 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012020211121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4141405 + ... + 7692546.

It is an arithmetic number, because the mean of its divisors is an integer number (2001168619008).

Almost surely, 2^{21012020211021} is an apocalyptic number.

21012020211021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21012020211021 is a deficient number, since it is larger than the sum of its proper divisors (11006677693107).

21012020211021 is a wasteful number, since it uses less digits than its factorization.

21012020211021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11918512.

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 21012020211021 its reverse (12011202021012), we get a palindrome (33023222232033).

The spelling of 21012020211021 in words is "twenty-one trillion, twelve billion, twenty million, two hundred eleven thousand, twenty-one".