20556071 has 4 divisors (see below), whose sum is σ = 20581872. Its totient is φ = 20530272.

The previous prime is 20556059. The next prime is 20556079. The reversal of 20556071 is 17065502.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20556071 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 20556071.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20556079) 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, 11666 + ... + 13311.

It is an arithmetic number, because the mean of its divisors is an integer number (5145468).

Almost surely, 2^20556071 is an apocalyptic number.

20556071 is a deficient number, since it is larger than the sum of its proper divisors (25801).

20556071 is an equidigital number, since it uses as much as digits as its factorization.

20556071 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25800.

The product of its (nonzero) digits is 2100, while the sum is 26.

The square root of 20556071 is about 4533.8803468993. The cubic root of 20556071 is about 273.9344818217.

The spelling of 20556071 in words is "twenty million, five hundred fifty-six thousand, seventy-one".