13978309 has 4 divisors (see below), whose sum is σ = 14041216. Its totient is φ = 13915404.

The previous prime is 13978297. The next prime is 13978313. The reversal of 13978309 is 90387931.

13978309 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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.

It is a cyclic number.

It is not a de Polignac number, because 13978309 - 2¹⁵ = 13945541 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 (13978109) 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, 31119 + ... + 31564.

It is an arithmetic number, because the mean of its divisors is an integer number (3510304).

Almost surely, 2^13978309 is an apocalyptic number.

It is an amenable number.

13978309 is a deficient number, since it is larger than the sum of its proper divisors (62907).

13978309 is an equidigital number, since it uses as much as digits as its factorization.

13978309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 62906.

The product of its (nonzero) digits is 40824, while the sum is 40.

The square root of 13978309 is about 3738.7576813696. The cubic root of 13978309 is about 240.8896897070.

The spelling of 13978309 in words is "thirteen million, nine hundred seventy-eight thousand, three hundred nine".