21303153721 has 2 divisors, whose sum is σ = 21303153722. Its totient is φ = 21303153720.

The previous prime is 21303153701. The next prime is 21303153733. The reversal of 21303153721 is 12735130312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21007313721 + 295840000 = 144939^2 + 17200^2 .

It is a cyclic number.

It is not a de Polignac number, because 21303153721 - 2³¹ = 19155670073 is a prime.

It is a super-2 number, since 2×21303153721² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21303153721.

It is not a weakly prime, because it can be changed into another prime (21303153701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10651576860 + 10651576861.

It is an arithmetic number, because the mean of its divisors is an integer number (10651576861).

Almost surely, 2^21303153721 is an apocalyptic number.

It is an amenable number.

21303153721 is a deficient number, since it is larger than the sum of its proper divisors (1).

21303153721 is an equidigital number, since it uses as much as digits as its factorization.

21303153721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3780, while the sum is 28.

The spelling of 21303153721 in words is "twenty-one billion, three hundred three million, one hundred fifty-three thousand, seven hundred twenty-one".