21388086 has 12 divisors (see below), whose sum is σ = 46340892. Its totient is φ = 7129356.

The previous prime is 21388049. The next prime is 21388099. The reversal of 21388086 is 68088312.

It is a self number, because there is not a number n which added to its sum of digits gives 21388086.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 594096 + ... + 594131.

It is an arithmetic number, because the mean of its divisors is an integer number (3861741).

Almost surely, 2^21388086 is an apocalyptic number.

21388086 is an abundant number, since it is smaller than the sum of its proper divisors (24952806).

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

21388086 is a wasteful number, since it uses less digits than its factorization.

21388086 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1188235 (or 1188232 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 36.

The square root of 21388086 is about 4624.7255053679. The cubic root of 21388086 is about 277.5815781584.

The spelling of 21388086 in words is "twenty-one million, three hundred eighty-eight thousand, eighty-six".