21206626 has 16 divisors (see below), whose sum is σ = 36581184. Its totient is φ = 9031824.

The previous prime is 21206623. The next prime is 21206657. The reversal of 21206626 is 62660212.

It is a self number, because there is not a number n which added to its sum of digits gives 21206626.

It is not an unprimeable number, because it can be changed into a prime (21206623) 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, 2365 + ... + 6928.

It is an arithmetic number, because the mean of its divisors is an integer number (2286324).

Almost surely, 2^21206626 is an apocalyptic number.

21206626 is a deficient number, since it is larger than the sum of its proper divisors (15374558).

21206626 is a wasteful number, since it uses less digits than its factorization.

21206626 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9465.

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 21206626 is about 4605.0652546951. The cubic root of 21206626 is about 276.7943318167.

Adding to 21206626 its reverse (62660212), we get a palindrome (83866838).

The spelling of 21206626 in words is "twenty-one million, two hundred six thousand, six hundred twenty-six".