78019861 has 2 divisors, whose sum is σ = 78019862. Its totient is φ = 78019860.

The previous prime is 78019853. The next prime is 78019867. The reversal of 78019861 is 16891087.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 39765636 + 38254225 = 6306^2 + 6185^2 .

It is a cyclic number.

It is not a de Polignac number, because 78019861 - 2³ = 78019853 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78019867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39009930 + 39009931.

It is an arithmetic number, because the mean of its divisors is an integer number (39009931).

Almost surely, 2^78019861 is an apocalyptic number.

It is an amenable number.

78019861 is a deficient number, since it is larger than the sum of its proper divisors (1).

78019861 is an equidigital number, since it uses as much as digits as its factorization.

78019861 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24192, while the sum is 40.

The square root of 78019861 is about 8832.8852024692. The cubic root of 78019861 is about 427.3021297393.

The spelling of 78019861 in words is "seventy-eight million, nineteen thousand, eight hundred sixty-one".