21368918 has 4 divisors (see below), whose sum is σ = 32053380. Its totient is φ = 10684458.

The previous prime is 21368903. The next prime is 21368923. The reversal of 21368918 is 81986312.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5342228 + ... + 5342231.

It is an arithmetic number, because the mean of its divisors is an integer number (8013345).

Almost surely, 2^21368918 is an apocalyptic number.

21368918 is a deficient number, since it is larger than the sum of its proper divisors (10684462).

21368918 is a wasteful number, since it uses less digits than its factorization.

21368918 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10684461.

The product of its digits is 20736, while the sum is 38.

The square root of 21368918 is about 4622.6527016422. The cubic root of 21368918 is about 277.4986305157.

The spelling of 21368918 in words is "twenty-one million, three hundred sixty-eight thousand, nine hundred eighteen".