84778591 has 2 divisors, whose sum is σ = 84778592. Its totient is φ = 84778590.

The previous prime is 84778567. The next prime is 84778637. The reversal of 84778591 is 19587748.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 84778591 - 2⁵ = 84778559 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (84778501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42389295 + 42389296.

It is an arithmetic number, because the mean of its divisors is an integer number (42389296).

Almost surely, 2^84778591 is an apocalyptic number.

84778591 is a deficient number, since it is larger than the sum of its proper divisors (1).

84778591 is an equidigital number, since it uses as much as digits as its factorization.

84778591 is an evil number, because the sum of its binary digits is even.

The product of its digits is 564480, while the sum is 49.

The square root of 84778591 is about 9207.5290387813. The cubic root of 84778591 is about 439.3008714725.

The spelling of 84778591 in words is "eighty-four million, seven hundred seventy-eight thousand, five hundred ninety-one".