21381208 has 16 divisors (see below), whose sum is σ = 40166280. Its totient is φ = 10670208.

The previous prime is 21381203. The next prime is 21381209. The reversal of 21381208 is 80218312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21381203) 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, 2491 + ... + 6997.

Almost surely, 2^21381208 is an apocalyptic number.

It is an amenable number.

21381208 is a deficient number, since it is larger than the sum of its proper divisors (18785072).

21381208 is a wasteful number, since it uses less digits than its factorization.

21381208 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5106 (or 5102 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 25.

The square root of 21381208 is about 4623.9818338744. The cubic root of 21381208 is about 277.5518199901.

The spelling of 21381208 in words is "twenty-one million, three hundred eighty-one thousand, two hundred eight".