20872557 has 12 divisors (see below), whose sum is σ = 30461340. Its totient is φ = 13771008.

The previous prime is 20872499. The next prime is 20872571. The reversal of 20872557 is 75527802.

20872557 is a `hidden beast` number, since 20 + 87 + 2 + 557 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 4639716 + 16232841 = 2154^2 + 4029^2 .

It is not a de Polignac number, because 20872557 - 2⁷ = 20872429 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20872457) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11082 + ... + 12827.

It is an arithmetic number, because the mean of its divisors is an integer number (2538445).

Almost surely, 2^20872557 is an apocalyptic number.

It is an amenable number.

20872557 is a deficient number, since it is larger than the sum of its proper divisors (9588783).

20872557 is a wasteful number, since it uses less digits than its factorization.

20872557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24012 (or 24009 counting only the distinct ones).

The product of its (nonzero) digits is 39200, while the sum is 36.

The square root of 20872557 is about 4568.6493627767. The cubic root of 20872557 is about 275.3331807394. Note that the first 3 decimals are identical.

The spelling of 20872557 in words is "twenty million, eight hundred seventy-two thousand, five hundred fifty-seven".