21022012012021 has 4 divisors (see below), whose sum is σ = 21031228152844. Its totient is φ = 21012795871200.

The previous prime is 21022012011953. The next prime is 21022012012063. The reversal of 21022012012021 is 12021021022012.

It is a happy number.

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 14644291089796 + 6377720922225 = 3826786^2 + 2525415^2 .

It is a cyclic number.

It is not a de Polignac number, because 21022012012021 - 2²⁵ = 21021978457589 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21022012011986 and 21022012012004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21022012012121) 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, 4608066990 + ... + 4608071551.

It is an arithmetic number, because the mean of its divisors is an integer number (5257807038211).

Almost surely, 2^{21022012012021} is an apocalyptic number.

It is an amenable number.

21022012012021 is a deficient number, since it is larger than the sum of its proper divisors (9216140823).

21022012012021 is an equidigital number, since it uses as much as digits as its factorization.

21022012012021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9216140822.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21022012012021 its reverse (12021021022012), we get a palindrome (33043033034033).

Subtracting from 21022012012021 its reverse (12021021022012), we obtain a palindrome (9000990990009).

The spelling of 21022012012021 in words is "twenty-one trillion, twenty-two billion, twelve million, twelve thousand, twenty-one".