21738766 has 16 divisors (see below), whose sum is σ = 37537920. Its totient is φ = 9248760.

The previous prime is 21738763. The next prime is 21738803. The reversal of 21738766 is 66783712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21738763) 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 7 ways as a sum of consecutive naturals, for example, 3640 + ... + 7531.

It is an arithmetic number, because the mean of its divisors is an integer number (2346120).

Almost surely, 2^21738766 is an apocalyptic number.

21738766 is a deficient number, since it is larger than the sum of its proper divisors (15799154).

21738766 is a wasteful number, since it uses less digits than its factorization.

21738766 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11319.

The product of its digits is 84672, while the sum is 40.

The square root of 21738766 is about 4662.4849597613. The cubic root of 21738766 is about 279.0904414250.

It can be divided in two parts, 217 and 38766, that added together give a palindrome (38983).

The spelling of 21738766 in words is "twenty-one million, seven hundred thirty-eight thousand, seven hundred sixty-six".