21056395 has 4 divisors (see below), whose sum is σ = 25267680. Its totient is φ = 16845112.

The previous prime is 21056381. The next prime is 21056401. The reversal of 21056395 is 59365012.

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

It is a cyclic number.

It is not a de Polignac number, because 21056395 - 2⁵ = 21056363 is a prime.

It is a super-3 number, since 3×21056395³ (a number of 23 digits) contains 333 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 2105635 + ... + 2105644.

It is an arithmetic number, because the mean of its divisors is an integer number (6316920).

Almost surely, 2^21056395 is an apocalyptic number.

21056395 is a deficient number, since it is larger than the sum of its proper divisors (4211285).

21056395 is an equidigital number, since it uses as much as digits as its factorization.

21056395 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4211284.

The product of its (nonzero) digits is 8100, while the sum is 31.

The square root of 21056395 is about 4588.7247683861. The cubic root of 21056395 is about 276.1391643985.

The spelling of 21056395 in words is "twenty-one million, fifty-six thousand, three hundred ninety-five".