21381368 has 8 divisors (see below), whose sum is σ = 40090080. Its totient is φ = 10690680.

The previous prime is 21381361. The next prime is 21381379. The reversal of 21381368 is 86318312.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21381361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1336328 + ... + 1336343.

It is an arithmetic number, because the mean of its divisors is an integer number (5011260).

Almost surely, 2^21381368 is an apocalyptic number.

It is an amenable number.

21381368 is a deficient number, since it is larger than the sum of its proper divisors (18708712).

21381368 is a wasteful number, since it uses less digits than its factorization.

21381368 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2672677 (or 2672673 counting only the distinct ones).

The product of its digits is 6912, while the sum is 32.

The square root of 21381368 is about 4623.9991349480. Note that the first 3 decimals coincide. The cubic root of 21381368 is about 277.5525123143.

The spelling of 21381368 in words is "twenty-one million, three hundred eighty-one thousand, three hundred sixty-eight".