20512521 has 20 divisors (see below), whose sum is σ = 30856452. Its totient is φ = 13579488.

The previous prime is 20512517. The next prime is 20512529. The reversal of 20512521 is 12521502.

It can be written as a sum of positive squares in 2 ways, for example, as 9363600 + 11148921 = 3060^2 + 3339^2 .

It is not a de Polignac number, because 20512521 - 2² = 20512517 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 20512494 and 20512503.

It is not an unprimeable number, because it can be changed into a prime (20512529) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 11911 + ... + 13523.

Almost surely, 2^20512521 is an apocalyptic number.

It is an amenable number.

20512521 is a deficient number, since it is larger than the sum of its proper divisors (10343931).

20512521 is a wasteful number, since it uses less digits than its factorization.

20512521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1782 (or 1773 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 18.

The square root of 20512521 is about 4529.0750711376. The cubic root of 20512521 is about 273.7408929228.

The spelling of 20512521 in words is "twenty million, five hundred twelve thousand, five hundred twenty-one".