78897509 has 4 divisors (see below), whose sum is σ = 78934380. Its totient is φ = 78860640.

The previous prime is 78897503. The next prime is 78897517. The reversal of 78897509 is 90579887.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15249025 + 63648484 = 3905^2 + 7978^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78897509 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78897503) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15014 + ... + 19575.

It is an arithmetic number, because the mean of its divisors is an integer number (19733595).

Almost surely, 2^78897509 is an apocalyptic number.

It is an amenable number.

78897509 is a deficient number, since it is larger than the sum of its proper divisors (36871).

78897509 is a wasteful number, since it uses less digits than its factorization.

78897509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36870.

The product of its (nonzero) digits is 1270080, while the sum is 53.

The square root of 78897509 is about 8882.4269769022. The cubic root of 78897509 is about 428.8984043720.

The spelling of 78897509 in words is "seventy-eight million, eight hundred ninety-seven thousand, five hundred nine".