21406366 has 16 divisors (see below), whose sum is σ = 34509456. Its totient is φ = 9922176.

The previous prime is 21406361. The next prime is 21406367. The reversal of 21406366 is 66360412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21406361) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2421 + ... + 6976.

It is an arithmetic number, because the mean of its divisors is an integer number (2156841).

Almost surely, 2^21406366 is an apocalyptic number.

21406366 is a deficient number, since it is larger than the sum of its proper divisors (13103090).

21406366 is a wasteful number, since it uses less digits than its factorization.

21406366 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9483.

The product of its (nonzero) digits is 5184, while the sum is 28.

The square root of 21406366 is about 4626.7014167763. The cubic root of 21406366 is about 277.6606369130.

Adding to 21406366 its reverse (66360412), we get a palindrome (87766778).

The spelling of 21406366 in words is "twenty-one million, four hundred six thousand, three hundred sixty-six".