19983981 has 4 divisors (see below), whose sum is σ = 26645312. Its totient is φ = 13322652.

The previous prime is 19983973. The next prime is 19983983. The reversal of 19983981 is 18938991.

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.

It is not a de Polignac number, because 19983981 - 2³ = 19983973 is a prime.

It is a super-2 number, since 2×19983981² = 798718993216722, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 19983981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19983983) 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, 3330661 + ... + 3330666.

It is an arithmetic number, because the mean of its divisors is an integer number (6661328).

Almost surely, 2^19983981 is an apocalyptic number.

It is an amenable number.

19983981 is a deficient number, since it is larger than the sum of its proper divisors (6661331).

19983981 is an equidigital number, since it uses as much as digits as its factorization.

19983981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6661330.

The product of its digits is 139968, while the sum is 48.

The square root of 19983981 is about 4470.3446175882. The cubic root of 19983981 is about 271.3692718761.

The spelling of 19983981 in words is "nineteen million, nine hundred eighty-three thousand, nine hundred eighty-one".