20722171 has 2 divisors, whose sum is σ = 20722172. Its totient is φ = 20722170.

The previous prime is 20722129. The next prime is 20722181. The reversal of 20722171 is 17122702.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20722171 is a prime.

It is not a weakly prime, because it can be changed into another prime (20722181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10361085 + 10361086.

It is an arithmetic number, because the mean of its divisors is an integer number (10361086).

Almost surely, 2^20722171 is an apocalyptic number.

20722171 is a deficient number, since it is larger than the sum of its proper divisors (1).

20722171 is an equidigital number, since it uses as much as digits as its factorization.

20722171 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 392, while the sum is 22.

The square root of 20722171 is about 4552.1611351093. The cubic root of 20722171 is about 274.6703311230.

Adding to 20722171 its reverse (17122702), we get a palindrome (37844873).

The spelling of 20722171 in words is "twenty million, seven hundred twenty-two thousand, one hundred seventy-one".