21296521 has 4 divisors (see below), whose sum is σ = 21596544. Its totient is φ = 20996500.

The previous prime is 21296501. The next prime is 21296533. The reversal of 21296521 is 12569212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21296521 - 2⁵ = 21296489 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21296521.

It is not an unprimeable number, because it can be changed into a prime (21296501) 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, 149905 + ... + 150046.

It is an arithmetic number, because the mean of its divisors is an integer number (5399136).

Almost surely, 2^21296521 is an apocalyptic number.

It is an amenable number.

21296521 is a deficient number, since it is larger than the sum of its proper divisors (300023).

21296521 is an equidigital number, since it uses as much as digits as its factorization.

21296521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 300022.

The product of its digits is 2160, while the sum is 28.

The square root of 21296521 is about 4614.8153809226. The cubic root of 21296521 is about 277.1848913540.

The spelling of 21296521 in words is "twenty-one million, two hundred ninety-six thousand, five hundred twenty-one".