28239971 has 2 divisors, whose sum is σ = 28239972. Its totient is φ = 28239970.

The previous prime is 28239899. The next prime is 28239973. The reversal of 28239971 is 17993282.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28239971 is a prime.

Together with 28239973, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (28239973) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14119985 + 14119986.

It is an arithmetic number, because the mean of its divisors is an integer number (14119986).

Almost surely, 2^28239971 is an apocalyptic number.

28239971 is a deficient number, since it is larger than the sum of its proper divisors (1).

28239971 is an equidigital number, since it uses as much as digits as its factorization.

28239971 is an evil number, because the sum of its binary digits is even.

The product of its digits is 54432, while the sum is 41.

The square root of 28239971 is about 5314.1293736604. The cubic root of 28239971 is about 304.5239226857.

The spelling of 28239971 in words is "twenty-eight million, two hundred thirty-nine thousand, nine hundred seventy-one".