201981 has 8 divisors (see below), whose sum is σ = 290080. Its totient is φ = 124272.

The previous prime is 201979. The next prime is 201997. The reversal of 201981 is 189102.

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

It is not a de Polignac number, because 201981 - 2¹ = 201979 is a prime.

It is a super-2 number, since 2×201981² = 81592648722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 201981.

It is not an unprimeable number, because it can be changed into a prime (201911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2551 + ... + 2628.

It is an arithmetic number, because the mean of its divisors is an integer number (36260).

2²⁰¹⁹⁸¹ is an apocalyptic number.

It is an amenable number.

201981 is a deficient number, since it is larger than the sum of its proper divisors (88099).

201981 is a wasteful number, since it uses less digits than its factorization.

201981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5195.

The product of its (nonzero) digits is 144, while the sum is 21.

The square root of 201981 is about 449.4229633652. The cubic root of 201981 is about 58.6728033927.

The spelling of 201981 in words is "two hundred one thousand, nine hundred eighty-one".