21054065 has 4 divisors (see below), whose sum is σ = 25264884. Its totient is φ = 16843248.

The previous prime is 21054049. The next prime is 21054067. The reversal of 21054065 is 56045012.

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 8579041 + 12475024 = 2929^2 + 3532^2 .

It is a cyclic number.

It is not a de Polignac number, because 21054065 - 2⁴ = 21054049 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21054065.

It is not an unprimeable number, because it can be changed into a prime (21054067) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2105402 + ... + 2105411.

It is an arithmetic number, because the mean of its divisors is an integer number (6316221).

Almost surely, 2^21054065 is an apocalyptic number.

It is an amenable number.

21054065 is a deficient number, since it is larger than the sum of its proper divisors (4210819).

21054065 is an equidigital number, since it uses as much as digits as its factorization.

21054065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4210818.

The product of its (nonzero) digits is 1200, while the sum is 23.

The square root of 21054065 is about 4588.4708781902. The cubic root of 21054065 is about 276.1289786095.

Adding to 21054065 its reverse (56045012), we get a palindrome (77099077).

The spelling of 21054065 in words is "twenty-one million, fifty-four thousand, sixty-five".