21030815321 has 2 divisors, whose sum is σ = 21030815322. Its totient is φ = 21030815320.

The previous prime is 21030815297. The next prime is 21030815329. The reversal of 21030815321 is 12351803012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20910606025 + 120209296 = 144605^2 + 10964^2 .

It is a cyclic number.

It is not a de Polignac number, because 21030815321 - 2⁶ = 21030815257 is a prime.

It is not a weakly prime, because it can be changed into another prime (21030815329) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10515407660 + 10515407661.

It is an arithmetic number, because the mean of its divisors is an integer number (10515407661).

Almost surely, 2^21030815321 is an apocalyptic number.

It is an amenable number.

21030815321 is a deficient number, since it is larger than the sum of its proper divisors (1).

21030815321 is an equidigital number, since it uses as much as digits as its factorization.

21030815321 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1440, while the sum is 26.

The spelling of 21030815321 in words is "twenty-one billion, thirty million, eight hundred fifteen thousand, three hundred twenty-one".