78591389 has 2 divisors, whose sum is σ = 78591390. Its totient is φ = 78591388.

The previous prime is 78591341. The next prime is 78591397. The reversal of 78591389 is 98319587.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 42471289 + 36120100 = 6517^2 + 6010^2 .

It is a cyclic number.

It is not a de Polignac number, because 78591389 - 2²⁰ = 77542813 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78561389) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39295694 + 39295695.

It is an arithmetic number, because the mean of its divisors is an integer number (39295695).

Almost surely, 2^78591389 is an apocalyptic number.

It is an amenable number.

78591389 is a deficient number, since it is larger than the sum of its proper divisors (1).

78591389 is an equidigital number, since it uses as much as digits as its factorization.

78591389 is an evil number, because the sum of its binary digits is even.

The product of its digits is 544320, while the sum is 50.

The square root of 78591389 is about 8865.1784528006. The cubic root of 78591389 is about 428.3429810374.

The spelling of 78591389 in words is "seventy-eight million, five hundred ninety-one thousand, three hundred eighty-nine".