78724417 has 2 divisors, whose sum is σ = 78724418. Its totient is φ = 78724416.

The previous prime is 78724411. The next prime is 78724453. The reversal of 78724417 is 71442787.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 69488896 + 9235521 = 8336^2 + 3039^2 .

It is a cyclic number.

It is not a de Polignac number, because 78724417 - 2¹⁵ = 78691649 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 78724417.

It is not a weakly prime, because it can be changed into another prime (78724411) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39362208 + 39362209.

It is an arithmetic number, because the mean of its divisors is an integer number (39362209).

Almost surely, 2^78724417 is an apocalyptic number.

It is an amenable number.

78724417 is a deficient number, since it is larger than the sum of its proper divisors (1).

78724417 is an equidigital number, since it uses as much as digits as its factorization.

78724417 is an evil number, because the sum of its binary digits is even.

The product of its digits is 87808, while the sum is 40.

The square root of 78724417 is about 8872.6781188094. The cubic root of 78724417 is about 428.5845235734.

The spelling of 78724417 in words is "seventy-eight million, seven hundred twenty-four thousand, four hundred seventeen".