20156181 has 4 divisors (see below), whose sum is σ = 26874912. Its totient is φ = 13437452.

The previous prime is 20156179. The next prime is 20156183. The reversal of 20156181 is 18165102.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (20156179) and next prime (20156183).

It is a cyclic number.

It is not a de Polignac number, because 20156181 - 2¹ = 20156179 is a prime.

It is a super-2 number, since 2×20156181² = 812543265009522, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20156183) 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, 3359361 + ... + 3359366.

It is an arithmetic number, because the mean of its divisors is an integer number (6718728).

Almost surely, 2^20156181 is an apocalyptic number.

It is an amenable number.

20156181 is a deficient number, since it is larger than the sum of its proper divisors (6718731).

20156181 is an equidigital number, since it uses as much as digits as its factorization.

20156181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6718730.

The product of its (nonzero) digits is 480, while the sum is 24.

The square root of 20156181 is about 4489.5635645350. The cubic root of 20156181 is about 272.1464978202.

The spelling of 20156181 in words is "twenty million, one hundred fifty-six thousand, one hundred eighty-one".