78339409 has 2 divisors, whose sum is σ = 78339410. Its totient is φ = 78339408.

The previous prime is 78339379. The next prime is 78339419. The reversal of 78339409 is 90493387.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 76300225 + 2039184 = 8735^2 + 1428^2 .

It is a cyclic number.

It is not a de Polignac number, because 78339409 - 2⁵ = 78339377 is a prime.

It is a super-2 number, since 2×78339409² = 12274126004938562, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78339419) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39169704 + 39169705.

It is an arithmetic number, because the mean of its divisors is an integer number (39169705).

Almost surely, 2^78339409 is an apocalyptic number.

It is an amenable number.

78339409 is a deficient number, since it is larger than the sum of its proper divisors (1).

78339409 is an equidigital number, since it uses as much as digits as its factorization.

78339409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 163296, while the sum is 43.

The square root of 78339409 is about 8850.9552591797. The cubic root of 78339409 is about 427.8847059672.

The spelling of 78339409 in words is "seventy-eight million, three hundred thirty-nine thousand, four hundred nine".