78444661 has 2 divisors, whose sum is σ = 78444662. Its totient is φ = 78444660.

The previous prime is 78444643. The next prime is 78444671. The reversal of 78444661 is 16644487.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 58140625 + 20304036 = 7625^2 + 4506^2 .

It is a cyclic number.

It is not a de Polignac number, because 78444661 - 2⁵ = 78444629 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78444631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39222330 + 39222331.

It is an arithmetic number, because the mean of its divisors is an integer number (39222331).

Almost surely, 2^78444661 is an apocalyptic number.

It is an amenable number.

78444661 is a deficient number, since it is larger than the sum of its proper divisors (1).

78444661 is an equidigital number, since it uses as much as digits as its factorization.

78444661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 129024, while the sum is 40.

The square root of 78444661 is about 8856.8990623129. The cubic root of 78444661 is about 428.0762467154.

The spelling of 78444661 in words is "seventy-eight million, four hundred forty-four thousand, six hundred sixty-one".