21605607 has 6 divisors (see below), whose sum is σ = 31208112. Its totient is φ = 14403732.

The previous prime is 21605593. The next prime is 21605611. The reversal of 21605607 is 70650612.

It is not a de Polignac number, because 21605607 - 2¹⁴ = 21589223 is a prime.

It is a zygodrome in base 3.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21605627) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1200303 + ... + 1200320.

It is an arithmetic number, because the mean of its divisors is an integer number (5201352).

Almost surely, 2^21605607 is an apocalyptic number.

21605607 is a deficient number, since it is larger than the sum of its proper divisors (9602505).

21605607 is a wasteful number, since it uses less digits than its factorization.

21605607 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2400629 (or 2400626 counting only the distinct ones).

The product of its (nonzero) digits is 2520, while the sum is 27.

The square root of 21605607 is about 4648.1831934639. The cubic root of 21605607 is about 278.5194255140.

The spelling of 21605607 in words is "twenty-one million, six hundred five thousand, six hundred seven".