20616181 has 4 divisors (see below), whose sum is σ = 20752864. Its totient is φ = 20479500.

The previous prime is 20616179. The next prime is 20616191. The reversal of 20616181 is 18161602.

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, and also an emirpimes, since its reverse is a distinct semiprime: 18161602 = 2 ⋅9080801.

It is a cyclic number.

It is not a de Polignac number, because 20616181 - 2¹ = 20616179 is a prime.

It is a super-2 number, since 2×20616181² = 850053838049522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20616161) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 68115 + ... + 68416.

It is an arithmetic number, because the mean of its divisors is an integer number (5188216).

Almost surely, 2^20616181 is an apocalyptic number.

It is an amenable number.

20616181 is a deficient number, since it is larger than the sum of its proper divisors (136683).

20616181 is a wasteful number, since it uses less digits than its factorization.

20616181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136682.

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 20616181 is about 4540.5044873890. The cubic root of 20616181 is about 274.2012347692.

Adding to 20616181 its reverse (18161602), we get a palindrome (38777783).

The spelling of 20616181 in words is "twenty million, six hundred sixteen thousand, one hundred eighty-one".