21536605 has 8 divisors (see below), whose sum is σ = 25871832. Its totient is φ = 17210688.

The previous prime is 21536573. The next prime is 21536621. The reversal of 21536605 is 50663512.

It can be written as a sum of positive squares in 4 ways, for example, as 9847044 + 11689561 = 3138^2 + 3419^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21536605 - 2⁵ = 21536573 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4699 + ... + 8071.

It is an arithmetic number, because the mean of its divisors is an integer number (3233979).

Almost surely, 2^21536605 is an apocalyptic number.

It is an amenable number.

21536605 is a deficient number, since it is larger than the sum of its proper divisors (4335227).

21536605 is a wasteful number, since it uses less digits than its factorization.

21536605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4655.

The product of its (nonzero) digits is 5400, while the sum is 28.

The square root of 21536605 is about 4640.7547877474. The cubic root of 21536605 is about 278.2226060650. Note that the first 3 decimals are identical.

The spelling of 21536605 in words is "twenty-one million, five hundred thirty-six thousand, six hundred five".