78440561 has 8 divisors (see below), whose sum is σ = 79591680. Its totient is φ = 77294512.

The previous prime is 78440507. The next prime is 78440581. The reversal of 78440561 is 16504487.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 78440561 - 2¹⁸ = 78178417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78440581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 38771 + ... + 40743.

It is an arithmetic number, because the mean of its divisors is an integer number (9948960).

Almost surely, 2^78440561 is an apocalyptic number.

It is an amenable number.

78440561 is a deficient number, since it is larger than the sum of its proper divisors (1151119).

78440561 is a wasteful number, since it uses less digits than its factorization.

78440561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2535.

The product of its (nonzero) digits is 26880, while the sum is 35.

The square root of 78440561 is about 8856.6676013047. The cubic root of 78440561 is about 428.0687886205.

The spelling of 78440561 in words is "seventy-eight million, four hundred forty thousand, five hundred sixty-one".