25521021009 has 81 divisors (see below), whose sum is σ = 41805907689. Its totient is φ = 14991221520.

The previous prime is 25521020999. The next prime is 25521021013. The reversal of 25521021009 is 90012012552.

The square root of 25521021009 is 159753.

It is a perfect power (a square), and thus also a powerful number.

25521021009 is a `hidden beast` number, since 2 + 552 + 1 + 0 + 2 + 100 + 9 = 666.

It is not a de Polignac number, because 25521021009 - 2⁷ = 25521020881 is a prime.

It is not an unprimeable number, because it can be changed into a prime (25521021079) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 247776852 + ... + 247776954.

Almost surely, 2^25521021009 is an apocalyptic number.

25521021009 is the 159753-rd square number.

25521021009 is the 79877-th centered octagonal number.

It is an amenable number.

25521021009 is a deficient number, since it is larger than the sum of its proper divisors (16284886680).

25521021009 is a wasteful number, since it uses less digits than its factorization.

25521021009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 328 (or 164 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 27.

The spelling of 25521021009 in words is "twenty-five billion, five hundred twenty-one million, twenty-one thousand, nine".