21860636 has 24 divisors (see below), whose sum is σ = 44905056. Its totient is φ = 9115200.

The previous prime is 21860609. The next prime is 21860647. The reversal of 21860636 is 63606812.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 9515 + ... + 11586.

It is an arithmetic number, because the mean of its divisors is an integer number (1871044).

Almost surely, 2^21860636 is an apocalyptic number.

It is an amenable number.

21860636 is an abundant number, since it is smaller than the sum of its proper divisors (23044420).

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

21860636 is a wasteful number, since it uses less digits than its factorization.

21860636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21149 (or 21147 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 32.

The square root of 21860636 is about 4675.5359051129. The cubic root of 21860636 is about 279.6110074579.

The spelling of 21860636 in words is "twenty-one million, eight hundred sixty thousand, six hundred thirty-six".