78717981 has 16 divisors (see below), whose sum is σ = 108337088. Its totient is φ = 50803200.

The previous prime is 78717979. The next prime is 78718001. The reversal of 78717981 is 18971787.

It is not a de Polignac number, because 78717981 - 2¹ = 78717979 is a prime.

It is a super-3 number, since 3×78717981³ (a number of 25 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 78717981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78717911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21741 + ... + 25101.

It is an arithmetic number, because the mean of its divisors is an integer number (6771068).

Almost surely, 2^78717981 is an apocalyptic number.

It is an amenable number.

78717981 is a deficient number, since it is larger than the sum of its proper divisors (29619107).

78717981 is a wasteful number, since it uses less digits than its factorization.

78717981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3612.

The product of its digits is 197568, while the sum is 48.

The square root of 78717981 is about 8872.3154249609. The cubic root of 78717981 is about 428.5728438207.

The spelling of 78717981 in words is "seventy-eight million, seven hundred seventeen thousand, nine hundred eighty-one".