78429661 has 2 divisors, whose sum is σ = 78429662. Its totient is φ = 78429660.

The previous prime is 78429649. The next prime is 78429671. The reversal of 78429661 is 16692487.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 73633561 + 4796100 = 8581^2 + 2190^2 .

It is a cyclic number.

It is not a de Polignac number, because 78429661 - 2²³ = 70041053 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78429671) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39214830 + 39214831.

It is an arithmetic number, because the mean of its divisors is an integer number (39214831).

Almost surely, 2^78429661 is an apocalyptic number.

It is an amenable number.

78429661 is a deficient number, since it is larger than the sum of its proper divisors (1).

78429661 is an equidigital number, since it uses as much as digits as its factorization.

78429661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 145152, while the sum is 43.

The square root of 78429661 is about 8856.0522243266. The cubic root of 78429661 is about 428.0489597382.

The spelling of 78429661 in words is "seventy-eight million, four hundred twenty-nine thousand, six hundred sixty-one".