21053806 has 8 divisors (see below), whose sum is σ = 31829760. Its totient is φ = 10443888.

The previous prime is 21053783. The next prime is 21053831. The reversal of 21053806 is 60835012.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 41191 + ... + 41698.

It is an arithmetic number, because the mean of its divisors is an integer number (3978720).

Almost surely, 2^21053806 is an apocalyptic number.

21053806 is a deficient number, since it is larger than the sum of its proper divisors (10775954).

21053806 is a wasteful number, since it uses less digits than its factorization.

21053806 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83018.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 21053806 is about 4588.4426551936. The cubic root of 21053806 is about 276.1278463230.

Adding to 21053806 its reverse (60835012), we get a palindrome (81888818).

The spelling of 21053806 in words is "twenty-one million, fifty-three thousand, eight hundred six".