84978109 has 2 divisors, whose sum is σ = 84978110. Its totient is φ = 84978108.

The previous prime is 84978107. The next prime is 84978137. The reversal of 84978109 is 90187948.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 76510009 + 8468100 = 8747^2 + 2910^2 .

It is a cyclic number.

It is not a de Polignac number, because 84978109 - 2¹ = 84978107 is a prime.

Together with 84978107, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (84978107) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42489054 + 42489055.

It is an arithmetic number, because the mean of its divisors is an integer number (42489055).

Almost surely, 2^84978109 is an apocalyptic number.

It is an amenable number.

84978109 is a deficient number, since it is larger than the sum of its proper divisors (1).

84978109 is an equidigital number, since it uses as much as digits as its factorization.

84978109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 145152, while the sum is 46.

The square root of 84978109 is about 9218.3571746814. The cubic root of 84978109 is about 439.6452184855.

The spelling of 84978109 in words is "eighty-four million, nine hundred seventy-eight thousand, one hundred nine".