21522643 has 4 divisors (see below), whose sum is σ = 21536008. Its totient is φ = 21509280.

The previous prime is 21522619. The next prime is 21522671. The reversal of 21522643 is 34622512.

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 21522643 - 2⁹ = 21522131 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21522673) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3873 + ... + 7618.

It is an arithmetic number, because the mean of its divisors is an integer number (5384002).

Almost surely, 2^21522643 is an apocalyptic number.

21522643 is a deficient number, since it is larger than the sum of its proper divisors (13365).

21522643 is a wasteful number, since it uses less digits than its factorization.

21522643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13364.

The product of its digits is 2880, while the sum is 25.

The square root of 21522643 is about 4639.2502627041. The cubic root of 21522643 is about 278.1624699422.

The spelling of 21522643 in words is "twenty-one million, five hundred twenty-two thousand, six hundred forty-three".