21026806 has 12 divisors (see below), whose sum is σ = 33288732. Its totient is φ = 9959724.

The previous prime is 21026801. The next prime is 21026821. The reversal of 21026806 is 60862012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21026801) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 13840 + ... + 15283.

It is an arithmetic number, because the mean of its divisors is an integer number (2774061).

Almost surely, 2^21026806 is an apocalyptic number.

21026806 is a deficient number, since it is larger than the sum of its proper divisors (12261926).

21026806 is a wasteful number, since it uses less digits than its factorization.

21026806 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29163 (or 29144 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 21026806 is about 4585.4995365827. The cubic root of 21026806 is about 276.0097577591.

Adding to 21026806 its reverse (60862012), we get a palindrome (81888818).

The spelling of 21026806 in words is "twenty-one million, twenty-six thousand, eight hundred six".