21213013021 has 2 divisors, whose sum is σ = 21213013022. Its totient is φ = 21213013020.

The previous prime is 21213012983. The next prime is 21213013039. The reversal of 21213013021 is 12031031212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20451860100 + 761152921 = 143010^2 + 27589^2 .

It is a cyclic number.

It is not a de Polignac number, because 21213013021 - 2⁷ = 21213012893 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21213012986 and 21213013004.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21213013051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606506510 + 10606506511.

It is an arithmetic number, because the mean of its divisors is an integer number (10606506511).

Almost surely, 2^21213013021 is an apocalyptic number.

It is an amenable number.

21213013021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21213013021 is an equidigital number, since it uses as much as digits as its factorization.

21213013021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72, while the sum is 16.

Adding to 21213013021 its reverse (12031031212), we get a palindrome (33244044233).

The spelling of 21213013021 in words is "twenty-one billion, two hundred thirteen million, thirteen thousand, twenty-one".