20805156 has 36 divisors (see below), whose sum is σ = 54879552. Its totient is φ = 6633264.

The previous prime is 20805121. The next prime is 20805167. The reversal of 20805156 is 65150802.

It is a tau number, because it is divible by the number of its divisors (36).

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 11736 + ... + 13391.

It is an arithmetic number, because the mean of its divisors is an integer number (1524432).

Almost surely, 2^20805156 is an apocalyptic number.

It is an amenable number.

20805156 is an abundant number, since it is smaller than the sum of its proper divisors (34074396).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20805156 is a wasteful number, since it uses less digits than its factorization.

20805156 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25160 (or 25155 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 27.

The square root of 20805156 is about 4561.2669292643. The cubic root of 20805156 is about 275.0364954319.

Adding to 20805156 its reverse (65150802), we get a palindrome (85955958).

The spelling of 20805156 in words is "twenty million, eight hundred five thousand, one hundred fifty-six".