21545636 has 12 divisors (see below), whose sum is σ = 43091328. Its totient is φ = 9233832.

The previous prime is 21545621. The next prime is 21545653. The reversal of 21545636 is 63654512.

21545636 is an admirable number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 384716 + ... + 384771.

It is an arithmetic number, because the mean of its divisors is an integer number (3590944).

Almost surely, 2^21545636 is an apocalyptic number.

It is an amenable number.

21545636 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21545636 is a wasteful number, since it uses less digits than its factorization.

21545636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 769498 (or 769496 counting only the distinct ones).

The product of its digits is 21600, while the sum is 32.

The square root of 21545636 is about 4641.7276955892. The cubic root of 21545636 is about 278.2614898976.

The spelling of 21545636 in words is "twenty-one million, five hundred forty-five thousand, six hundred thirty-six".