21021212111021 has 4 divisors (see below), whose sum is σ = 21056189170044. Its totient is φ = 20986235052000.

The previous prime is 21021212111017. The next prime is 21021212111051. The reversal of 21021212111021 is 12011121212012.

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 12131637302500 + 8889574808521 = 3483050^2 + 2981539^2 .

It is a cyclic number.

It is not a de Polignac number, because 21021212111021 - 2² = 21021212111017 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 (21021212111051) 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, 17488528610 + ... + 17488529811.

It is an arithmetic number, because the mean of its divisors is an integer number (5264047292511).

Almost surely, 2^{21021212111021} is an apocalyptic number.

It is an amenable number.

21021212111021 is a deficient number, since it is larger than the sum of its proper divisors (34977059023).

21021212111021 is an equidigital number, since it uses as much as digits as its factorization.

21021212111021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34977059022.

The product of its (nonzero) digits is 32, while the sum is 17.

Adding to 21021212111021 its reverse (12011121212012), we get a palindrome (33032333323033).

The spelling of 21021212111021 in words is "twenty-one trillion, twenty-one billion, two hundred twelve million, one hundred eleven thousand, twenty-one".