11919981 has 8 divisors (see below), whose sum is σ = 15923520. Its totient is φ = 7931552.

The previous prime is 11919967. The next prime is 11919983. The reversal of 11919981 is 18991911.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 11919981 - 2¹³ = 11911789 is a prime.

It is a super-2 number, since 2×11919981² = 284171894080722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11919983) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1785 + ... + 5198.

It is an arithmetic number, because the mean of its divisors is an integer number (1990440).

Almost surely, 2^11919981 is an apocalyptic number.

It is an amenable number.

11919981 is a deficient number, since it is larger than the sum of its proper divisors (4003539).

11919981 is an equidigital number, since it uses as much as digits as its factorization.

11919981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7555.

The product of its digits is 5832, while the sum is 39.

The square root of 11919981 is about 3452.5325487242. The cubic root of 11919981 is about 228.4328304660.

It can be divided in two parts, 119 and 19981, that added together give a triangular number (20100 = T₂₀₀).

The spelling of 11919981 in words is "eleven million, nine hundred nineteen thousand, nine hundred eighty-one".