21011365 has 4 divisors (see below), whose sum is σ = 25213644. Its totient is φ = 16809088.

The previous prime is 21011357. The next prime is 21011383. The reversal of 21011365 is 56311012.

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

It can be written as a sum of positive squares in 2 ways, for example, as 7001316 + 14010049 = 2646^2 + 3743^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011365 - 2³ = 21011357 is a prime.

It is a Duffinian number.

It is a congruent 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, 2101132 + ... + 2101141.

It is an arithmetic number, because the mean of its divisors is an integer number (6303411).

Almost surely, 2^21011365 is an apocalyptic number.

It is an amenable number.

21011365 is a deficient number, since it is larger than the sum of its proper divisors (4202279).

21011365 is an equidigital number, since it uses as much as digits as its factorization.

21011365 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4202278.

The product of its (nonzero) digits is 180, while the sum is 19.

The square root of 21011365 is about 4583.8155503903. The cubic root of 21011365 is about 275.9421787787.

Adding to 21011365 its reverse (56311012), we get a palindrome (77322377).

The spelling of 21011365 in words is "twenty-one million, eleven thousand, three hundred sixty-five".