78317881 has 2 divisors, whose sum is σ = 78317882. Its totient is φ = 78317880.

The previous prime is 78317851. The next prime is 78317959. The reversal of 78317881 is 18871387.

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., 67322025 + 10995856 = 8205^2 + 3316^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78317881 is a prime.

It is a super-2 number, since 2×78317881² = 12267380968660322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78317851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39158940 + 39158941.

It is an arithmetic number, because the mean of its divisors is an integer number (39158941).

Almost surely, 2^78317881 is an apocalyptic number.

It is an amenable number.

78317881 is a deficient number, since it is larger than the sum of its proper divisors (1).

78317881 is an equidigital number, since it uses as much as digits as its factorization.

78317881 is an evil number, because the sum of its binary digits is even.

The product of its digits is 75264, while the sum is 43.

The square root of 78317881 is about 8849.7390357004. The cubic root of 78317881 is about 427.8455075357.

The spelling of 78317881 in words is "seventy-eight million, three hundred seventeen thousand, eight hundred eighty-one".