21132806 has 4 divisors (see below), whose sum is σ = 31699212. Its totient is φ = 10566402.

The previous prime is 21132773. The next prime is 21132817. The reversal of 21132806 is 60823112.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5283200 + ... + 5283203.

It is an arithmetic number, because the mean of its divisors is an integer number (7924803).

Almost surely, 2^21132806 is an apocalyptic number.

21132806 is a deficient number, since it is larger than the sum of its proper divisors (10566406).

21132806 is a wasteful number, since it uses less digits than its factorization.

21132806 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10566405.

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 21132806 is about 4597.0431801322. The cubic root of 21132806 is about 276.4727858922.

Adding to 21132806 its reverse (60823112), we get a palindrome (81955918).

The spelling of 21132806 in words is "twenty-one million, one hundred thirty-two thousand, eight hundred six".