21013033021 has 2 divisors, whose sum is σ = 21013033022. Its totient is φ = 21013033020.

The previous prime is 21013032979. The next prime is 21013033043. The reversal of 21013033021 is 12033031012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15810296121 + 5202736900 = 125739^2 + 72130^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21013033021 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21013032986 and 21013033004.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21013033051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506516510 + 10506516511.

It is an arithmetic number, because the mean of its divisors is an integer number (10506516511).

Almost surely, 2^21013033021 is an apocalyptic number.

It is an amenable number.

21013033021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21013033021 is an equidigital number, since it uses as much as digits as its factorization.

21013033021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 108, while the sum is 16.

Adding to 21013033021 its reverse (12033031012), we get a palindrome (33046064033).

The spelling of 21013033021 in words is "twenty-one billion, thirteen million, thirty-three thousand, twenty-one".