78509401 has 4 divisors (see below), whose sum is σ = 78681652. Its totient is φ = 78337152.

The previous prime is 78509369. The next prime is 78509407. The reversal of 78509401 is 10490587.

It is a happy number.

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 68492176 + 10017225 = 8276^2 + 3165^2 .

It is a cyclic number.

It is not a de Polignac number, because 78509401 - 2⁵ = 78509369 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78509407) 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, 85440 + ... + 86353.

It is an arithmetic number, because the mean of its divisors is an integer number (19670413).

Almost surely, 2^78509401 is an apocalyptic number.

It is an amenable number.

78509401 is a deficient number, since it is larger than the sum of its proper divisors (172251).

78509401 is a wasteful number, since it uses less digits than its factorization.

78509401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172250.

The product of its (nonzero) digits is 10080, while the sum is 34.

The square root of 78509401 is about 8860.5530865742. The cubic root of 78509401 is about 428.1939774204.

Adding to 78509401 its reverse (10490587), we get a palindrome (88999988).

The spelling of 78509401 in words is "seventy-eight million, five hundred nine thousand, four hundred one".