78721597 has 2 divisors, whose sum is σ = 78721598. Its totient is φ = 78721596.

The previous prime is 78721549. The next prime is 78721603. The reversal of 78721597 is 79512787.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 42889401 + 35832196 = 6549^2 + 5986^2 .

It is a cyclic number.

It is not a de Polignac number, because 78721597 - 2⁷ = 78721469 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78721297) 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, 39360798 + 39360799.

It is an arithmetic number, because the mean of its divisors is an integer number (39360799).

Almost surely, 2^78721597 is an apocalyptic number.

It is an amenable number.

78721597 is a deficient number, since it is larger than the sum of its proper divisors (1).

78721597 is an equidigital number, since it uses as much as digits as its factorization.

78721597 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 246960, while the sum is 46.

The square root of 78721597 is about 8872.5192025715. The cubic root of 78721597 is about 428.5794060473.

The spelling of 78721597 in words is "seventy-eight million, seven hundred twenty-one thousand, five hundred ninety-seven".