21525705 has 24 divisors (see below), whose sum is σ = 37489608. Its totient is φ = 11425536.

The previous prime is 21525703. The next prime is 21525719. The reversal of 21525705 is 50752512.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 622521 + 20903184 = 789^2 + 4572^2 .

It is not a de Polignac number, because 21525705 - 2¹ = 21525703 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21525703) 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 23 ways as a sum of consecutive naturals, for example, 9459 + ... + 11511.

It is an arithmetic number, because the mean of its divisors is an integer number (1562067).

Almost surely, 2^21525705 is an apocalyptic number.

It is an amenable number.

21525705 is a deficient number, since it is larger than the sum of its proper divisors (15963903).

21525705 is a wasteful number, since it uses less digits than its factorization.

21525705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2297 (or 2294 counting only the distinct ones).

The product of its (nonzero) digits is 3500, while the sum is 27.

The square root of 21525705 is about 4639.5802611874. The cubic root of 21525705 is about 278.1756605944.

The spelling of 21525705 in words is "twenty-one million, five hundred twenty-five thousand, seven hundred five".