20772161 has 4 divisors (see below), whose sum is σ = 21022512. Its totient is φ = 20521812.

The previous prime is 20772137. The next prime is 20772173. The reversal of 20772161 is 16127702.

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: 16127702 = 2 ⋅8063851.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20772161 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20772161.

It is not an unprimeable number, because it can be changed into a prime (20772061) 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, 125051 + ... + 125216.

It is an arithmetic number, because the mean of its divisors is an integer number (5255628).

Almost surely, 2^20772161 is an apocalyptic number.

It is an amenable number.

20772161 is a deficient number, since it is larger than the sum of its proper divisors (250351).

20772161 is an equidigital number, since it uses as much as digits as its factorization.

20772161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 250350.

The product of its (nonzero) digits is 1176, while the sum is 26.

The square root of 20772161 is about 4557.6486262107. The cubic root of 20772161 is about 274.8910245902.

Adding to 20772161 its reverse (16127702), we get a palindrome (36899863).

The spelling of 20772161 in words is "twenty million, seven hundred seventy-two thousand, one hundred sixty-one".