21867940 has 48 divisors (see below), whose sum is σ = 48408192. Its totient is φ = 8281856.

The previous prime is 21867931. The next prime is 21867941. The reversal of 21867940 is 4976812.

It is a hoax number, since the sum of its digits (37) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21867940.

It is not an unprimeable number, because it can be changed into a prime (21867941) 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 15 ways as a sum of consecutive naturals, for example, 62847 + ... + 63193.

It is an arithmetic number, because the mean of its divisors is an integer number (1008504).

Almost surely, 2^21867940 is an apocalyptic number.

21867940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21867940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24204096).

21867940 is an abundant number, since it is smaller than the sum of its proper divisors (26540252).

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

21867940 is a wasteful number, since it uses less digits than its factorization.

21867940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 516 (or 514 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 37.

The square root of 21867940 is about 4676.3169268132. The cubic root of 21867940 is about 279.6421448775.

The spelling of 21867940 in words is "twenty-one million, eight hundred sixty-seven thousand, nine hundred forty".