21366388 has 24 divisors (see below), whose sum is σ = 39513600. Its totient is φ = 10092768.

The previous prime is 21366377. The next prime is 21366391. The reversal of 21366388 is 88366312.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3493 + ... + 7411.

It is an arithmetic number, because the mean of its divisors is an integer number (1646400).

Almost surely, 2^21366388 is an apocalyptic number.

It is an amenable number.

21366388 is a deficient number, since it is larger than the sum of its proper divisors (18147212).

21366388 is a wasteful number, since it uses less digits than its factorization.

21366388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3999 (or 3997 counting only the distinct ones).

The product of its digits is 41472, while the sum is 37.

The square root of 21366388 is about 4622.3790411432. The cubic root of 21366388 is about 277.4876784833.

The spelling of 21366388 in words is "twenty-one million, three hundred sixty-six thousand, three hundred eighty-eight".