21636330 has 32 divisors (see below), whose sum is σ = 54186624. Its totient is φ = 5518656.

The previous prime is 21636319. The next prime is 21636331. The reversal of 21636330 is 3363612.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21636330.

It is not an unprimeable number, because it can be changed into a prime (21636331) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14989 + ... + 16368.

It is an arithmetic number, because the mean of its divisors is an integer number (1693332).

Almost surely, 2^21636330 is an apocalyptic number.

21636330 is an abundant number, since it is smaller than the sum of its proper divisors (32550294).

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

21636330 is a wasteful number, since it uses less digits than its factorization.

21636330 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31390.

The product of its (nonzero) digits is 1944, while the sum is 24.

The square root of 21636330 is about 4651.4868590592. The cubic root of 21636330 is about 278.6513804511.

Adding to 21636330 its reverse (3363612), we get a palindrome (24999942).

The spelling of 21636330 in words is "twenty-one million, six hundred thirty-six thousand, three hundred thirty".