78988781 has 2 divisors, whose sum is σ = 78988782. Its totient is φ = 78988780.

The previous prime is 78988769. The next prime is 78988799. The reversal of 78988781 is 18788987.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 76282756 + 2706025 = 8734^2 + 1645^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78988781 is a prime.

It is a super-2 number, since 2×78988781² = 12478455047731922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78988711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39494390 + 39494391.

It is an arithmetic number, because the mean of its divisors is an integer number (39494391).

Almost surely, 2^78988781 is an apocalyptic number.

It is an amenable number.

78988781 is a deficient number, since it is larger than the sum of its proper divisors (1).

78988781 is an equidigital number, since it uses as much as digits as its factorization.

78988781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1806336, while the sum is 56.

The square root of 78988781 is about 8887.5632768493. The cubic root of 78988781 is about 429.0637299525.

The spelling of 78988781 in words is "seventy-eight million, nine hundred eighty-eight thousand, seven hundred eighty-one".