101981 has 8 divisors (see below), whose sum is σ = 113664. Its totient is φ = 90720.

The previous prime is 101977. The next prime is 101987. The reversal of 101981 is 189101.

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 101981 - 2² = 101977 is a prime.

It is a super-2 number, since 2×101981² = 20800248722, which contains 22 as substring.

It is an Ulam number.

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 101981.

It is not an unprimeable number, because it can be changed into a prime (101987) 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, 740 + ... + 866.

It is an arithmetic number, because the mean of its divisors is an integer number (14208).

2¹⁰¹⁹⁸¹ is an apocalyptic number.

101981 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

101981 is a deficient number, since it is larger than the sum of its proper divisors (11683).

101981 is a wasteful number, since it uses less digits than its factorization.

101981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 211.

The product of its (nonzero) digits is 72, while the sum is 20.

The square root of 101981 is about 319.3446414143. The cubic root of 101981 is about 46.7203859843.

It can be divided in two parts, 10 and 1981, that added together give a palindrome (1991).

The spelling of 101981 in words is "one hundred one thousand, nine hundred eighty-one".