21605536 has 12 divisors (see below), whose sum is σ = 42535962. Its totient is φ = 10802752.

The previous prime is 21605531. The next prime is 21605561. The reversal of 21605536 is 63550612.

It can be written as a sum of positive squares in only one way, i.e., 19184400 + 2421136 = 4380^2 + 1556^2 .

It is a super-3 number, since 3×21605536³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (21605531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 337555 + ... + 337618.

Almost surely, 2^21605536 is an apocalyptic number.

It is an amenable number.

21605536 is a deficient number, since it is larger than the sum of its proper divisors (20930426).

21605536 is an equidigital number, since it uses as much as digits as its factorization.

21605536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 675183 (or 675175 counting only the distinct ones).

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

The square root of 21605536 is about 4648.1755560650. The cubic root of 21605536 is about 278.5191204250.

The spelling of 21605536 in words is "twenty-one million, six hundred five thousand, five hundred thirty-six".