20601521 has 4 divisors (see below), whose sum is σ = 20653812. Its totient is φ = 20549232.

The previous prime is 20601517. The next prime is 20601523. The reversal of 20601521 is 12510602.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6948496 + 13653025 = 2636^2 + 3695^2 .

It is a cyclic number.

It is not a de Polignac number, because 20601521 - 2² = 20601517 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20601521.

It is not an unprimeable number, because it can be changed into a prime (20601523) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25550 + ... + 26343.

It is an arithmetic number, because the mean of its divisors is an integer number (5163453).

Almost surely, 2^20601521 is an apocalyptic number.

It is an amenable number.

20601521 is a deficient number, since it is larger than the sum of its proper divisors (52291).

20601521 is an equidigital number, since it uses as much as digits as its factorization.

20601521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52290.

The product of its (nonzero) digits is 120, while the sum is 17.

The square root of 20601521 is about 4538.8898422412. The cubic root of 20601521 is about 274.1362252622.

The spelling of 20601521 in words is "twenty million, six hundred one thousand, five hundred twenty-one".