78900509 has 4 divisors (see below), whose sum is σ = 79041216. Its totient is φ = 78759804.

The previous prime is 78900499. The next prime is 78900529. The reversal of 78900509 is 90500987.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 90500987 = 67 ⋅1350761.

It is a cyclic number.

It is not a de Polignac number, because 78900509 - 2¹² = 78896413 is a prime.

It is a Duffinian number.

It is a plaindrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78900529) 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, 69509 + ... + 70634.

It is an arithmetic number, because the mean of its divisors is an integer number (19760304).

Almost surely, 2^78900509 is an apocalyptic number.

It is an amenable number.

78900509 is a deficient number, since it is larger than the sum of its proper divisors (140707).

78900509 is a wasteful number, since it uses less digits than its factorization.

78900509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 140706.

The product of its (nonzero) digits is 22680, while the sum is 38.

The square root of 78900509 is about 8882.5958480615. The cubic root of 78900509 is about 428.9038404494.

The spelling of 78900509 in words is "seventy-eight million, nine hundred thousand, five hundred nine".