78788257 has 2 divisors, whose sum is σ = 78788258. Its totient is φ = 78788256.

The previous prime is 78788249. The next prime is 78788287. The reversal of 78788257 is 75288787.

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., 57775201 + 21013056 = 7601^2 + 4584^2 .

It is a cyclic number.

It is not a de Polignac number, because 78788257 - 2³ = 78788249 is a prime.

It is not a weakly prime, because it can be changed into another prime (78788287) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39394128 + 39394129.

It is an arithmetic number, because the mean of its divisors is an integer number (39394129).

Almost surely, 2^78788257 is an apocalyptic number.

It is an amenable number.

78788257 is a deficient number, since it is larger than the sum of its proper divisors (1).

78788257 is an equidigital number, since it uses as much as digits as its factorization.

78788257 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1756160, while the sum is 52.

The square root of 78788257 is about 8876.2749506761. The cubic root of 78788257 is about 428.7003429699.

The spelling of 78788257 in words is "seventy-eight million, seven hundred eighty-eight thousand, two hundred fifty-seven".