28221971 has 2 divisors, whose sum is σ = 28221972. Its totient is φ = 28221970.

The previous prime is 28221967. The next prime is 28222021. The reversal of 28221971 is 17912282.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 28221971 - 2² = 28221967 is a prime.

It is not a weakly prime, because it can be changed into another prime (28221911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14110985 + 14110986.

It is an arithmetic number, because the mean of its divisors is an integer number (14110986).

Almost surely, 2^28221971 is an apocalyptic number.

28221971 is a deficient number, since it is larger than the sum of its proper divisors (1).

28221971 is an equidigital number, since it uses as much as digits as its factorization.

28221971 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4032, while the sum is 32.

The square root of 28221971 is about 5312.4355054909. The cubic root of 28221971 is about 304.4592083176.

It can be divided in two parts, 28221 and 971, that added together give a palindrome (29192).

The spelling of 28221971 in words is "twenty-eight million, two hundred twenty-one thousand, nine hundred seventy-one".