20706561 has 36 divisors (see below), whose sum is σ = 33524400. Its totient is φ = 12279168.

The previous prime is 20706559. The next prime is 20706563. The reversal of 20706561 is 16560702.

20706561 is a `hidden beast` number, since 2 + 0 + 7 + 0 + 656 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (20706559) and next prime (20706563).

It is not a de Polignac number, because 20706561 - 2¹ = 20706559 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20706563) 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 35 ways as a sum of consecutive naturals, for example, 49210 + ... + 49628.

Almost surely, 2^20706561 is an apocalyptic number.

It is an amenable number.

20706561 is a deficient number, since it is larger than the sum of its proper divisors (12817839).

20706561 is a wasteful number, since it uses less digits than its factorization.

20706561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 478 (or 458 counting only the distinct ones).

The product of its (nonzero) digits is 2520, while the sum is 27.

The square root of 20706561 is about 4550.4462418536. The cubic root of 20706561 is about 274.6013441278.

The spelling of 20706561 in words is "twenty million, seven hundred six thousand, five hundred sixty-one".