84378991 has 2 divisors, whose sum is σ = 84378992. Its totient is φ = 84378990.

The previous prime is 84378979. The next prime is 84379003. The reversal of 84378991 is 19987348.

It is a happy number.

It is a balanced prime because it is at equal distance from previous prime (84378979) and next prime (84379003).

It is a cyclic number.

It is not a de Polignac number, because 84378991 - 2⁷ = 84378863 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (84378901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42189495 + 42189496.

It is an arithmetic number, because the mean of its divisors is an integer number (42189496).

Almost surely, 2^84378991 is an apocalyptic number.

84378991 is a deficient number, since it is larger than the sum of its proper divisors (1).

84378991 is an equidigital number, since it uses as much as digits as its factorization.

84378991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 435456, while the sum is 49.

The square root of 84378991 is about 9185.8037753917. The cubic root of 84378991 is about 438.6095760331.

The spelling of 84378991 in words is "eighty-four million, three hundred seventy-eight thousand, nine hundred ninety-one".