20509525 has 12 divisors (see below), whose sum is σ = 26309700. Its totient is φ = 15841280.

The previous prime is 20509523. The next prime is 20509543. The reversal of 20509525 is 52590502.

It can be written as a sum of positive squares in 6 ways, for example, as 421201 + 20088324 = 649^2 + 4482^2 .

It is not a de Polignac number, because 20509525 - 2¹ = 20509523 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20509493 and 20509502.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20509523) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 13420 + ... + 14869.

It is an arithmetic number, because the mean of its divisors is an integer number (2192475).

Almost surely, 2^20509525 is an apocalyptic number.

20509525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

20509525 is a deficient number, since it is larger than the sum of its proper divisors (5800175).

20509525 is a wasteful number, since it uses less digits than its factorization.

20509525 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28328 (or 28323 counting only the distinct ones).

The product of its (nonzero) digits is 4500, while the sum is 28.

The square root of 20509525 is about 4528.7443072004. The cubic root of 20509525 is about 273.7275650039.

It can be divided in two parts, 205095 and 25, that added together give a triangular number (205120 = T₆₄₀).

The spelling of 20509525 in words is "twenty million, five hundred nine thousand, five hundred twenty-five".