21034565 has 8 divisors (see below), whose sum is σ = 25266168. Its totient is φ = 16811200.

The previous prime is 21034561. The next prime is 21034567. The reversal of 21034565 is 56543012.

It can be written as a sum of positive squares in 4 ways, for example, as 3587236 + 17447329 = 1894^2 + 4177^2 .

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

It is not a de Polignac number, because 21034565 - 2² = 21034561 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21034561) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 8399 + ... + 10611.

It is an arithmetic number, because the mean of its divisors is an integer number (3158271).

Almost surely, 2^21034565 is an apocalyptic number.

It is an amenable number.

21034565 is a deficient number, since it is larger than the sum of its proper divisors (4231603).

21034565 is a wasteful number, since it uses less digits than its factorization.

21034565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4119.

The product of its (nonzero) digits is 3600, while the sum is 26.

The square root of 21034565 is about 4586.3454950538. The cubic root of 21034565 is about 276.0437032594.

Adding to 21034565 its reverse (56543012), we get a palindrome (77577577).

The spelling of 21034565 in words is "twenty-one million, thirty-four thousand, five hundred sixty-five".