21147944 has 16 divisors (see below), whose sum is σ = 39705120. Its totient is φ = 10559920.

The previous prime is 21147943. The next prime is 21147967. The reversal of 21147944 is 44974112.

It is a self number, because there is not a number n which added to its sum of digits gives 21147944.

It is not an unprimeable number, because it can be changed into a prime (21147941) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7517 + ... + 9939.

It is an arithmetic number, because the mean of its divisors is an integer number (2481570).

Almost surely, 2^21147944 is an apocalyptic number.

It is an amenable number.

21147944 is a deficient number, since it is larger than the sum of its proper divisors (18557176).

21147944 is a wasteful number, since it uses less digits than its factorization.

21147944 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3520 (or 3516 counting only the distinct ones).

The product of its digits is 8064, while the sum is 32.

The square root of 21147944 is about 4598.6893785078. The cubic root of 21147944 is about 276.5387851116.

The spelling of 21147944 in words is "twenty-one million, one hundred forty-seven thousand, nine hundred forty-four".