12399981 has 8 divisors (see below), whose sum is σ = 18036384. Its totient is φ = 7515120.

The previous prime is 12399977. The next prime is 12399983. The reversal of 12399981 is 18999321.

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

It is not a de Polignac number, because 12399981 - 2² = 12399977 is a prime.

It is a super-2 number, since 2×12399981² = 307519057600722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12399983) 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, 187846 + ... + 187911.

It is an arithmetic number, because the mean of its divisors is an integer number (2254548).

Almost surely, 2^12399981 is an apocalyptic number.

12399981 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

12399981 is a deficient number, since it is larger than the sum of its proper divisors (5636403).

12399981 is a wasteful number, since it uses less digits than its factorization.

12399981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 375771.

The product of its digits is 34992, while the sum is 42.

The square root of 12399981 is about 3521.3606745121. The cubic root of 12399981 is about 231.4587872343.

It can be divided in two parts, 12 and 399981, that added together give a palindrome (399993).

The spelling of 12399981 in words is "twelve million, three hundred ninety-nine thousand, nine hundred eighty-one".