11981475578 has 4 divisors (see below), whose sum is σ = 17972213370. Its totient is φ = 5990737788.

The previous prime is 11981475559. The next prime is 11981475589. The reversal of 11981475578 is 87557418911.

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 only one way, i.e., 11973392929 + 8082649 = 109423^2 + 2843^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2995368893 + ... + 2995368896.

Almost surely, 2^11981475578 is an apocalyptic number.

11981475578 is a deficient number, since it is larger than the sum of its proper divisors (5990737792).

11981475578 is an equidigital number, since it uses as much as digits as its factorization.

11981475578 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5990737791.

The product of its digits is 2822400, while the sum is 56.

The spelling of 11981475578 in words is "eleven billion, nine hundred eighty-one million, four hundred seventy-five thousand, five hundred seventy-eight".