78329857 has 2 divisors, whose sum is σ = 78329858. Its totient is φ = 78329856.

The previous prime is 78329831. The next prime is 78329861. The reversal of 78329857 is 75892387.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 59459521 + 18870336 = 7711^2 + 4344^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78329857 is a prime.

It is a super-2 number, since 2×78329857² = 12271132995280898, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 78329857.

It is not a weakly prime, because it can be changed into another prime (78329057) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39164928 + 39164929.

It is an arithmetic number, because the mean of its divisors is an integer number (39164929).

Almost surely, 2^78329857 is an apocalyptic number.

It is an amenable number.

78329857 is a deficient number, since it is larger than the sum of its proper divisors (1).

78329857 is an equidigital number, since it uses as much as digits as its factorization.

78329857 is an evil number, because the sum of its binary digits is even.

The product of its digits is 846720, while the sum is 49.

The square root of 78329857 is about 8850.4156399573. The cubic root of 78329857 is about 427.8673144615.

It can be divided in two parts, 7832 and 9857, that added together give a square (17689 = 133²).

The spelling of 78329857 in words is "seventy-eight million, three hundred twenty-nine thousand, eight hundred fifty-seven".