21847940 has 12 divisors (see below), whose sum is σ = 45880716. Its totient is φ = 8739168.

The previous prime is 21847939. The next prime is 21847961. The reversal of 21847940 is 4974812.

It can be written as a sum of positive squares in 2 ways, for example, as 10137856 + 11710084 = 3184^2 + 3422^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21847940.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 546179 + ... + 546218.

It is an arithmetic number, because the mean of its divisors is an integer number (3823393).

Almost surely, 2^21847940 is an apocalyptic number.

21847940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21847940 is an abundant number, since it is smaller than the sum of its proper divisors (24032776).

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

21847940 is a wasteful number, since it uses less digits than its factorization.

21847940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1092406 (or 1092404 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 35.

The square root of 21847940 is about 4674.1780026011. The cubic root of 21847940 is about 279.5568670873.

The spelling of 21847940 in words is "twenty-one million, eight hundred forty-seven thousand, nine hundred forty".