21388886 has 8 divisors (see below), whose sum is σ = 32950560. Its totient is φ = 10405368.

The previous prime is 21388883. The next prime is 21388891. The reversal of 21388886 is 68888312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21388883) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 144446 + ... + 144593.

It is an arithmetic number, because the mean of its divisors is an integer number (4118820).

Almost surely, 2^21388886 is an apocalyptic number.

21388886 is a deficient number, since it is larger than the sum of its proper divisors (11561674).

21388886 is a wasteful number, since it uses less digits than its factorization.

21388886 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 289078.

The product of its digits is 147456, while the sum is 44.

The square root of 21388886 is about 4624.8119961789. The cubic root of 21388886 is about 277.5850390025.

It can be divided in two parts, 2 and 1388886, that multiplied together give a palindrome (2777772).

The spelling of 21388886 in words is "twenty-one million, three hundred eighty-eight thousand, eight hundred eighty-six".