84271721 has 2 divisors, whose sum is σ = 84271722. Its totient is φ = 84271720.

The previous prime is 84271699. The next prime is 84271723. The reversal of 84271721 is 12717248.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 49000000 + 35271721 = 7000^2 + 5939^2 .

It is a cyclic number.

It is not a de Polignac number, because 84271721 - 2⁶ = 84271657 is a prime.

It is a Sophie Germain prime.

Together with 84271723, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is equal to p_4903880 and since 84271721 and 4903880 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (84271723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42135860 + 42135861.

It is an arithmetic number, because the mean of its divisors is an integer number (42135861).

Almost surely, 2^84271721 is an apocalyptic number.

It is an amenable number.

84271721 is a deficient number, since it is larger than the sum of its proper divisors (1).

84271721 is an equidigital number, since it uses as much as digits as its factorization.

84271721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6272, while the sum is 32.

The square root of 84271721 is about 9179.9630173547. The cubic root of 84271721 is about 438.4236308484.

Adding to 84271721 its reverse (12717248), we get a palindrome (96988969).

The spelling of 84271721 in words is "eighty-four million, two hundred seventy-one thousand, seven hundred twenty-one".