21465505 has 4 divisors (see below), whose sum is σ = 25758612. Its totient is φ = 17172400.

The previous prime is 21465503. The next prime is 21465517. The reversal of 21465505 is 50556412.

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 14432401 + 7033104 = 3799^2 + 2652^2 .

It is not a de Polignac number, because 21465505 - 2¹ = 21465503 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21465503) 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 3 ways as a sum of consecutive naturals, for example, 2146546 + ... + 2146555.

It is an arithmetic number, because the mean of its divisors is an integer number (6439653).

Almost surely, 2^21465505 is an apocalyptic number.

It is an amenable number.

21465505 is a deficient number, since it is larger than the sum of its proper divisors (4293107).

21465505 is an equidigital number, since it uses as much as digits as its factorization.

21465505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4293106.

The product of its (nonzero) digits is 6000, while the sum is 28.

The square root of 21465505 is about 4633.0880630525. The cubic root of 21465505 is about 277.9160978969.

The spelling of 21465505 in words is "twenty-one million, four hundred sixty-five thousand, five hundred five".