13561978 has 4 divisors (see below), whose sum is σ = 20342970. Its totient is φ = 6780988.

The previous prime is 13561967. The next prime is 13561981. The reversal of 13561978 is 87916531.

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

It can be written as a sum of positive squares in only one way, i.e., 9653449 + 3908529 = 3107^2 + 1977^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 13561978.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3390493 + ... + 3390496.

Almost surely, 2^13561978 is an apocalyptic number.

13561978 is a deficient number, since it is larger than the sum of its proper divisors (6780992).

13561978 is an equidigital number, since it uses as much as digits as its factorization.

13561978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6780991.

The product of its digits is 45360, while the sum is 40.

The square root of 13561978 is about 3682.6590936442. The cubic root of 13561978 is about 238.4739865590.

The spelling of 13561978 in words is "thirteen million, five hundred sixty-one thousand, nine hundred seventy-eight".