21725565 has 8 divisors (see below), whose sum is σ = 34760928. Its totient is φ = 11586960.

The previous prime is 21725551. The next prime is 21725567. The reversal of 21725565 is 56552712.

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

It is not a de Polignac number, because 21725565 - 2⁵ = 21725533 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21725567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 724171 + ... + 724200.

It is an arithmetic number, because the mean of its divisors is an integer number (4345116).

Almost surely, 2^21725565 is an apocalyptic number.

It is an amenable number.

21725565 is a deficient number, since it is larger than the sum of its proper divisors (13035363).

21725565 is a wasteful number, since it uses less digits than its factorization.

21725565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1448379.

The product of its digits is 21000, while the sum is 33.

The square root of 21725565 is about 4661.0690833756. The cubic root of 21725565 is about 279.0339368541.

The spelling of 21725565 in words is "twenty-one million, seven hundred twenty-five thousand, five hundred sixty-five".