84517991 has 2 divisors, whose sum is σ = 84517992. Its totient is φ = 84517990.

The previous prime is 84517969. The next prime is 84518009. The reversal of 84517991 is 19971548.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 84517991 - 2²⁶ = 17409127 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (84517921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42258995 + 42258996.

It is an arithmetic number, because the mean of its divisors is an integer number (42258996).

Almost surely, 2^84517991 is an apocalyptic number.

84517991 is a deficient number, since it is larger than the sum of its proper divisors (1).

84517991 is an equidigital number, since it uses as much as digits as its factorization.

84517991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90720, while the sum is 44.

The square root of 84517991 is about 9193.3666847352. The cubic root of 84517991 is about 438.8502887332.

The spelling of 84517991 in words is "eighty-four million, five hundred seventeen thousand, nine hundred ninety-one".