28721171 has 2 divisors, whose sum is σ = 28721172. Its totient is φ = 28721170.

The previous prime is 28721137. The next prime is 28721191. The reversal of 28721171 is 17112782.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 28721171 - 2¹⁰ = 28720147 is a prime.

It is a super-2 number, since 2×28721171² = 1649811327222482, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (28721131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14360585 + 14360586.

It is an arithmetic number, because the mean of its divisors is an integer number (14360586).

Almost surely, 2^28721171 is an apocalyptic number.

28721171 is a deficient number, since it is larger than the sum of its proper divisors (1).

28721171 is an equidigital number, since it uses as much as digits as its factorization.

28721171 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1568, while the sum is 29.

The square root of 28721171 is about 5359.2136550057. The cubic root of 28721171 is about 306.2438534932.

The spelling of 28721171 in words is "twenty-eight million, seven hundred twenty-one thousand, one hundred seventy-one".