39981281 has 4 divisors (see below), whose sum is σ = 39994032. Its totient is φ = 39968532.

The previous prime is 39981247. The next prime is 39981287. The reversal of 39981281 is 18218993.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 18218993 = 13 ⋅1401461.

It is a cyclic number.

It is not a de Polignac number, because 39981281 - 2⁶ = 39981217 is a prime.

It is a super-2 number, since 2×39981281² = 3197005660801922, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (39981287) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1970 + ... + 9156.

It is an arithmetic number, because the mean of its divisors is an integer number (9998508).

Almost surely, 2^39981281 is an apocalyptic number.

It is an amenable number.

39981281 is a deficient number, since it is larger than the sum of its proper divisors (12751).

39981281 is an equidigital number, since it uses as much as digits as its factorization.

39981281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12750.

The product of its digits is 31104, while the sum is 41.

The square root of 39981281 is about 6323.0752802730. The cubic root of 39981281 is about 341.9418326117.

The spelling of 39981281 in words is "thirty-nine million, nine hundred eighty-one thousand, two hundred eighty-one".