78920817 has 16 divisors (see below), whose sum is σ = 111834432. Its totient is φ = 49333760.

The previous prime is 78920801. The next prime is 78920837. The reversal of 78920817 is 71802987.

It is a cyclic number.

It is not a de Polignac number, because 78920817 - 2⁴ = 78920801 is a prime.

It is not an unprimeable number, because it can be changed into a prime (78920837) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11578 + ... + 17084.

It is an arithmetic number, because the mean of its divisors is an integer number (6989652).

Almost surely, 2^78920817 is an apocalyptic number.

It is an amenable number.

78920817 is a deficient number, since it is larger than the sum of its proper divisors (32913615).

78920817 is a wasteful number, since it uses less digits than its factorization.

78920817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5808.

The product of its (nonzero) digits is 56448, while the sum is 42.

The square root of 78920817 is about 8883.7389088154. The cubic root of 78920817 is about 428.9406354465.

The spelling of 78920817 in words is "seventy-eight million, nine hundred twenty thousand, eight hundred seventeen".