28721971 has 2 divisors, whose sum is σ = 28721972. Its totient is φ = 28721970.

The previous prime is 28721933. The next prime is 28721981. The reversal of 28721971 is 17912782.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 28721971 - 2¹³ = 28713779 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 28721971.

It is not a weakly prime, because it can be changed into another prime (28721921) 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 as a sum of consecutive naturals, namely, 14360985 + 14360986.

It is an arithmetic number, because the mean of its divisors is an integer number (14360986).

Almost surely, 2^28721971 is an apocalyptic number.

28721971 is a deficient number, since it is larger than the sum of its proper divisors (1).

28721971 is an equidigital number, since it uses as much as digits as its factorization.

28721971 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14112, while the sum is 37.

The square root of 28721971 is about 5359.2882923015. The cubic root of 28721971 is about 306.2466968407.

It can be divided in two parts, 28721 and 971, that added together give a palindrome (29692).

The spelling of 28721971 in words is "twenty-eight million, seven hundred twenty-one thousand, nine hundred seventy-one".