78156409 has 2 divisors, whose sum is σ = 78156410. Its totient is φ = 78156408.

The previous prime is 78156391. The next prime is 78156427. The reversal of 78156409 is 90465187.

It is a balanced prime because it is at equal distance from previous prime (78156391) and next prime (78156427).

It can be written as a sum of positive squares in only one way, i.e., 55830784 + 22325625 = 7472^2 + 4725^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78156409 is a prime.

It is a super-2 number, since 2×78156409² = 12216848535550562, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (78156439) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39078204 + 39078205.

It is an arithmetic number, because the mean of its divisors is an integer number (39078205).

Almost surely, 2^78156409 is an apocalyptic number.

It is an amenable number.

78156409 is a deficient number, since it is larger than the sum of its proper divisors (1).

78156409 is an equidigital number, since it uses as much as digits as its factorization.

78156409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 60480, while the sum is 40.

The square root of 78156409 is about 8840.6113476388. The cubic root of 78156409 is about 427.5512682036.

The spelling of 78156409 in words is "seventy-eight million, one hundred fifty-six thousand, four hundred nine".