11991538 has 16 divisors (see below), whose sum is σ = 19446336. Its totient is φ = 5513040.

The previous prime is 11991523. The next prime is 11991583. The reversal of 11991538 is 83519911.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 11991497 and 11991506.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7345 + ... + 8827.

It is an arithmetic number, because the mean of its divisors is an integer number (1215396).

Almost surely, 2^11991538 is an apocalyptic number.

11991538 is a deficient number, since it is larger than the sum of its proper divisors (7454798).

11991538 is a wasteful number, since it uses less digits than its factorization.

11991538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1809.

The product of its digits is 9720, while the sum is 37.

The square root of 11991538 is about 3462.8800152474. The cubic root of 11991538 is about 228.8890215679.

The spelling of 11991538 in words is "eleven million, nine hundred ninety-one thousand, five hundred thirty-eight".