21605361 has 8 divisors (see below), whose sum is σ = 28928640. Its totient is φ = 14342832.

The previous prime is 21605329. The next prime is 21605369. The reversal of 21605361 is 16350612.

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

It is not a de Polignac number, because 21605361 - 2⁵ = 21605329 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21605369) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14350 + ... + 15783.

It is an arithmetic number, because the mean of its divisors is an integer number (3616080).

Almost surely, 2^21605361 is an apocalyptic number.

It is an amenable number.

21605361 is a deficient number, since it is larger than the sum of its proper divisors (7323279).

21605361 is a wasteful number, since it uses less digits than its factorization.

21605361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30375.

The product of its (nonzero) digits is 1080, while the sum is 24.

The square root of 21605361 is about 4648.1567314367. The cubic root of 21605361 is about 278.5183684421.

Adding to 21605361 its reverse (16350612), we get a palindrome (37955973).

The spelling of 21605361 in words is "twenty-one million, six hundred five thousand, three hundred sixty-one".