21528719 has 4 divisors (see below), whose sum is σ = 21541800. Its totient is φ = 21515640.

The previous prime is 21528707. The next prime is 21528733. The reversal of 21528719 is 91782512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21528719 - 2¹² = 21524623 is a prime.

It is a super-2 number, since 2×21528719² = 926971483561922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21528739) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3644 + ... + 7505.

It is an arithmetic number, because the mean of its divisors is an integer number (5385450).

Almost surely, 2^21528719 is an apocalyptic number.

21528719 is a deficient number, since it is larger than the sum of its proper divisors (13081).

21528719 is a wasteful number, since it uses less digits than its factorization.

21528719 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13080.

The product of its digits is 10080, while the sum is 35.

The square root of 21528719 is about 4639.9050636840. The cubic root of 21528719 is about 278.1886432480.

The spelling of 21528719 in words is "twenty-one million, five hundred twenty-eight thousand, seven hundred nineteen".