21528319 has 2 divisors, whose sum is σ = 21528320. Its totient is φ = 21528318.

The previous prime is 21528313. The next prime is 21528329. The reversal of 21528319 is 91382512.

21528319 is nontrivially palindromic in base 12.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21528319 is a prime.

It is a super-2 number, since 2×21528319² = 926937037931522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21528313) 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, 10764159 + 10764160.

It is an arithmetic number, because the mean of its divisors is an integer number (10764160).

Almost surely, 2^21528319 is an apocalyptic number.

21528319 is a deficient number, since it is larger than the sum of its proper divisors (1).

21528319 is an equidigital number, since it uses as much as digits as its factorization.

21528319 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4320, while the sum is 31.

The square root of 21528319 is about 4639.8619591535. The cubic root of 21528319 is about 278.1869203378.

The spelling of 21528319 in words is "twenty-one million, five hundred twenty-eight thousand, three hundred nineteen".