21123886 has 16 divisors (see below), whose sum is σ = 36292320. Its totient is φ = 9033120.

The previous prime is 21123871. The next prime is 21123887. The reversal of 21123886 is 68832112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123887) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6180 + ... + 8968.

It is an arithmetic number, because the mean of its divisors is an integer number (2268270).

Almost surely, 2^21123886 is an apocalyptic number.

21123886 is a deficient number, since it is larger than the sum of its proper divisors (15168434).

21123886 is a wasteful number, since it uses less digits than its factorization.

21123886 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3339.

The product of its digits is 4608, while the sum is 31.

The square root of 21123886 is about 4596.0728888911. The cubic root of 21123886 is about 276.4338813834.

Adding to 21123886 its reverse (68832112), we get a palindrome (89955998).

The spelling of 21123886 in words is "twenty-one million, one hundred twenty-three thousand, eight hundred eighty-six".