78204781 has 2 divisors, whose sum is σ = 78204782. Its totient is φ = 78204780.

The previous prime is 78204769. The next prime is 78204787. The reversal of 78204781 is 18740287.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 75429225 + 2775556 = 8685^2 + 1666^2 .

It is an emirp because it is prime and its reverse (18740287) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78204781 - 2⁷ = 78204653 is a prime.

It is a super-2 number, since 2×78204781² = 12231975542515922, 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 78204781.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78204787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39102390 + 39102391.

It is an arithmetic number, because the mean of its divisors is an integer number (39102391).

Almost surely, 2^78204781 is an apocalyptic number.

It is an amenable number.

78204781 is a deficient number, since it is larger than the sum of its proper divisors (1).

78204781 is an equidigital number, since it uses as much as digits as its factorization.

78204781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 25088, while the sum is 37.

The square root of 78204781 is about 8843.3467081190. The cubic root of 78204781 is about 427.6394556600.

The spelling of 78204781 in words is "seventy-eight million, two hundred four thousand, seven hundred eighty-one".