11981540 has 24 divisors (see below), whose sum is σ = 25297272. Its totient is φ = 4766720.

The previous prime is 11981443. The next prime is 11981587. The reversal of 11981540 is 4518911.

It can be written as a sum of positive squares in 4 ways, for example, as 8076964 + 3904576 = 2842^2 + 1976^2 .

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 7 ways as a sum of consecutive naturals, for example, 2420 + ... + 5460.

It is an arithmetic number, because the mean of its divisors is an integer number (1054053).

Almost surely, 2^11981540 is an apocalyptic number.

11981540 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

11981540 is an abundant number, since it is smaller than the sum of its proper divisors (13315732).

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

11981540 is a wasteful number, since it uses less digits than its factorization.

11981540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3247 (or 3245 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 29.

The square root of 11981540 is about 3461.4361181452. The cubic root of 11981540 is about 228.8253914556.

It can be divided in two parts, 11981 and 540, that added together give a palindrome (12521).

The spelling of 11981540 in words is "eleven million, nine hundred eighty-one thousand, five hundred forty".