20156161 has 4 divisors (see below), whose sum is σ = 20185300. Its totient is φ = 20127024.

The previous prime is 20156153. The next prime is 20156177. The reversal of 20156161 is 16165102.

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

It can be written as a sum of positive squares in 2 ways, for example, as 4601025 + 15555136 = 2145^2 + 3944^2 .

It is a cyclic number.

It is not a de Polignac number, because 20156161 - 2³ = 20156153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20156861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13506 + ... + 14923.

It is an arithmetic number, because the mean of its divisors is an integer number (5046325).

Almost surely, 2^20156161 is an apocalyptic number.

It is an amenable number.

20156161 is a deficient number, since it is larger than the sum of its proper divisors (29139).

20156161 is an equidigital number, since it uses as much as digits as its factorization.

20156161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29138.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 20156161 is about 4489.5613371464. The cubic root of 20156161 is about 272.1464078075.

The spelling of 20156161 in words is "twenty million, one hundred fifty-six thousand, one hundred sixty-one".