13431978 has 72 divisors (see below), whose sum is σ = 34420932. Its totient is φ = 3773952.

The previous prime is 13431967. The next prime is 13431991. The reversal of 13431978 is 87913431.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 13198689 + 233289 = 3633^2 + 483^2 .

It is a zygodrome in base 7.

It is an unprimeable number.

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 35 ways as a sum of consecutive naturals, for example, 85476 + ... + 85632.

Almost surely, 2^13431978 is an apocalyptic number.

13431978 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 13431978, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (17210466).

13431978 is an abundant number, since it is smaller than the sum of its proper divisors (20988954).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

13431978 is a wasteful number, since it uses less digits than its factorization.

13431978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 276 (or 266 counting only the distinct ones).

The product of its digits is 18144, while the sum is 36.

The square root of 13431978 is about 3664.9663027100. The cubic root of 13431978 is about 237.7095649837.

It can be divided in two parts, 1343 and 1978, that added together give a triangular number (3321 = T₈₁).

The spelling of 13431978 in words is "thirteen million, four hundred thirty-one thousand, nine hundred seventy-eight".