21328501 has 2 divisors, whose sum is σ = 21328502. Its totient is φ = 21328500.

The previous prime is 21328451. The next prime is 21328537. The reversal of 21328501 is 10582312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21298225 + 30276 = 4615^2 + 174^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21328501 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21328561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10664250 + 10664251.

It is an arithmetic number, because the mean of its divisors is an integer number (10664251).

Almost surely, 2^21328501 is an apocalyptic number.

It is an amenable number.

21328501 is a deficient number, since it is larger than the sum of its proper divisors (1).

21328501 is an equidigital number, since it uses as much as digits as its factorization.

21328501 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 21328501 is about 4618.2790084619. The cubic root of 21328501 is about 277.3235672039.

The spelling of 21328501 in words is "twenty-one million, three hundred twenty-eight thousand, five hundred one".