21385668 has 12 divisors (see below), whose sum is σ = 49899920. Its totient is φ = 7128552.

The previous prime is 21385649. The next prime is 21385681. The reversal of 21385668 is 86658312.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (12).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 891058 + ... + 891081.

Almost surely, 2^21385668 is an apocalyptic number.

It is an amenable number.

21385668 is an abundant number, since it is smaller than the sum of its proper divisors (28514252).

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

21385668 is a wasteful number, since it uses less digits than its factorization.

21385668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1782146 (or 1782144 counting only the distinct ones).

The product of its digits is 69120, while the sum is 39.

The square root of 21385668 is about 4624.4640770580. The cubic root of 21385668 is about 277.5711172324.

The spelling of 21385668 in words is "twenty-one million, three hundred eighty-five thousand, six hundred sixty-eight".