21295609 has 4 divisors (see below), whose sum is σ = 21871204. Its totient is φ = 20720016.

The previous prime is 21295607. The next prime is 21295627. The reversal of 21295609 is 90659212.

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 13483584 + 7812025 = 3672^2 + 2795^2 .

It is a cyclic number.

It is not a de Polignac number, because 21295609 - 2¹ = 21295607 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21295601) 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, 287742 + ... + 287815.

It is an arithmetic number, because the mean of its divisors is an integer number (5467801).

Almost surely, 2^21295609 is an apocalyptic number.

It is an amenable number.

21295609 is a deficient number, since it is larger than the sum of its proper divisors (575595).

21295609 is an equidigital number, since it uses as much as digits as its factorization.

21295609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 575594.

The product of its (nonzero) digits is 9720, while the sum is 34.

The square root of 21295609 is about 4614.7165676778. The cubic root of 21295609 is about 277.1809345852.

It can be divided in two parts, 21295 and 609, that added together give a square (21904 = 148²).

The spelling of 21295609 in words is "twenty-one million, two hundred ninety-five thousand, six hundred nine".