21539606 has 16 divisors (see below), whose sum is σ = 36384768. Its totient is φ = 9474600.

The previous prime is 21539593. The next prime is 21539611. The reversal of 21539606 is 60693512.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 15110 + ... + 16473.

It is an arithmetic number, because the mean of its divisors is an integer number (2274048).

Almost surely, 2^21539606 is an apocalyptic number.

21539606 is a deficient number, since it is larger than the sum of its proper divisors (14845162).

21539606 is a wasteful number, since it uses less digits than its factorization.

21539606 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31627.

The product of its (nonzero) digits is 9720, while the sum is 32.

The square root of 21539606 is about 4641.0781075091. The cubic root of 21539606 is about 278.2355283627.

The spelling of 21539606 in words is "twenty-one million, five hundred thirty-nine thousand, six hundred six".