21870936 has 48 divisors (see below), whose sum is σ = 59599800. Its totient is φ = 7245312.

The previous prime is 21870931. The next prime is 21870967. The reversal of 21870936 is 63907812.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21870936.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21870931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12040 + ... + 13736.

Almost surely, 2^21870936 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21870936, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29799900).

21870936 is an abundant number, since it is smaller than the sum of its proper divisors (37728864).

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

21870936 is a wasteful number, since it uses less digits than its factorization.

21870936 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1888 (or 1881 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 21870936 is about 4676.6372534119. The cubic root of 21870936 is about 279.6549150120.

The spelling of 21870936 in words is "twenty-one million, eight hundred seventy thousand, nine hundred thirty-six".