21325009 has 4 divisors (see below), whose sum is σ = 21480804. Its totient is φ = 21169216.

The previous prime is 21324983. The next prime is 21325013. The reversal of 21325009 is 90052312.

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 9628609 + 11696400 = 3103^2 + 3420^2 .

It is a cyclic number.

It is not a de Polignac number, because 21325009 - 2⁵ = 21324977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21325099) 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, 77692 + ... + 77965.

It is an arithmetic number, because the mean of its divisors is an integer number (5370201).

Almost surely, 2^21325009 is an apocalyptic number.

It is an amenable number.

21325009 is a deficient number, since it is larger than the sum of its proper divisors (155795).

21325009 is a wasteful number, since it uses less digits than its factorization.

21325009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 155794.

The product of its (nonzero) digits is 540, while the sum is 22.

The square root of 21325009 is about 4617.9009300763. The cubic root of 21325009 is about 277.3084314824.

The spelling of 21325009 in words is "twenty-one million, three hundred twenty-five thousand, nine".