20071521 has 12 divisors (see below), whose sum is σ = 29080272. Its totient is φ = 13340376.

The previous prime is 20071517. The next prime is 20071529. The reversal of 20071521 is 12517002.

It is not a de Polignac number, because 20071521 - 2² = 20071517 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20071494 and 20071503.

It is not an unprimeable number, because it can be changed into a prime (20071529) 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, 91 + ... + 6336.

It is an arithmetic number, because the mean of its divisors is an integer number (2423356).

Almost surely, 2^20071521 is an apocalyptic number.

It is an amenable number.

20071521 is a deficient number, since it is larger than the sum of its proper divisors (9008751).

20071521 is a wasteful number, since it uses less digits than its factorization.

20071521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6780 (or 6777 counting only the distinct ones).

The product of its (nonzero) digits is 140, while the sum is 18.

The square root of 20071521 is about 4480.1251098602. The cubic root of 20071521 is about 271.7649398352.

Adding to 20071521 its reverse (12517002), we get a palindrome (32588523).

The spelling of 20071521 in words is "twenty million, seventy-one thousand, five hundred twenty-one".