20126561 has 8 divisors (see below), whose sum is σ = 24771264. Its totient is φ = 15924240.

The previous prime is 20126527. The next prime is 20126563. The reversal of 20126561 is 16562102.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20126561 - 2⁶ = 20126497 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20126563) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 110495 + ... + 110676.

It is an arithmetic number, because the mean of its divisors is an integer number (3096408).

Almost surely, 2^20126561 is an apocalyptic number.

It is an amenable number.

20126561 is a deficient number, since it is larger than the sum of its proper divisors (4644703).

20126561 is a wasteful number, since it uses less digits than its factorization.

20126561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221191.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 20126561 is about 4486.2635901159. The cubic root of 20126561 is about 272.0131238261.

Adding to 20126561 its reverse (16562102), we get a palindrome (36688663).

It can be divided in two parts, 201 and 26561, that added together give a palindrome (26762).

The spelling of 20126561 in words is "twenty million, one hundred twenty-six thousand, five hundred sixty-one".