78999913 has 2 divisors, whose sum is σ = 78999914. Its totient is φ = 78999912.

The previous prime is 78999911. The next prime is 78999923. The reversal of 78999913 is 31999987.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 72046144 + 6953769 = 8488^2 + 2637^2 .

It is a cyclic number.

It is not a de Polignac number, because 78999913 - 2¹ = 78999911 is a prime.

Together with 78999911, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (78999911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39499956 + 39499957.

It is an arithmetic number, because the mean of its divisors is an integer number (39499957).

Almost surely, 2^78999913 is an apocalyptic number.

It is an amenable number.

78999913 is a deficient number, since it is larger than the sum of its proper divisors (1).

78999913 is an equidigital number, since it uses as much as digits as its factorization.

78999913 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1102248, while the sum is 55.

The square root of 78999913 is about 8888.1895231819. The cubic root of 78999913 is about 429.0838851907.

The spelling of 78999913 in words is "seventy-eight million, nine hundred ninety-nine thousand, nine hundred thirteen".