21051365 has 8 divisors (see below), whose sum is σ = 25320600. Its totient is φ = 16801792.

The previous prime is 21051353. The next prime is 21051383. The reversal of 21051365 is 56315012.

It can be written as a sum of positive squares in 4 ways, for example, as 494209 + 20557156 = 703^2 + 4534^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21051365 - 2¹⁸ = 20789221 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21051365.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2444 + ... + 6933.

It is an arithmetic number, because the mean of its divisors is an integer number (3165075).

Almost surely, 2^21051365 is an apocalyptic number.

It is an amenable number.

21051365 is a deficient number, since it is larger than the sum of its proper divisors (4269235).

21051365 is an equidigital number, since it uses as much as digits as its factorization.

21051365 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9831.

The product of its (nonzero) digits is 900, while the sum is 23.

The square root of 21051365 is about 4588.1766530943. The cubic root of 21051365 is about 276.1171743948.

Adding to 21051365 its reverse (56315012), we get a palindrome (77366377).

The spelling of 21051365 in words is "twenty-one million, fifty-one thousand, three hundred sixty-five".