21034031021 has 2 divisors, whose sum is σ = 21034031022. Its totient is φ = 21034031020.

The previous prime is 21034030993. The next prime is 21034031023. The reversal of 21034031021 is 12013043012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18965145796 + 2068885225 = 137714^2 + 45485^2 .

It is a cyclic number.

It is not a de Polignac number, because 21034031021 - 2¹⁴ = 21034014637 is a prime.

Together with 21034031023, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21034031023) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10517015510 + 10517015511.

It is an arithmetic number, because the mean of its divisors is an integer number (10517015511).

Almost surely, 2^21034031021 is an apocalyptic number.

It is an amenable number.

21034031021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21034031021 is an equidigital number, since it uses as much as digits as its factorization.

21034031021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 17.

Adding to 21034031021 its reverse (12013043012), we get a palindrome (33047074033).

The spelling of 21034031021 in words is "twenty-one billion, thirty-four million, thirty-one thousand, twenty-one".