137981 has 4 divisors (see below), whose sum is σ = 142464. Its totient is φ = 133500.

The previous prime is 137957. The next prime is 137983. The reversal of 137981 is 189731.

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 an emirpimes, since its reverse is a distinct semiprime: 189731 = 337 ⋅563.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-137981 is a prime.

It is a super-2 number, since 2×137981² = 38077512722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (137983) 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 3 ways as a sum of consecutive naturals, for example, 2195 + ... + 2256.

It is an arithmetic number, because the mean of its divisors is an integer number (35616).

2¹³⁷⁹⁸¹ is an apocalyptic number.

It is an amenable number.

137981 is a deficient number, since it is larger than the sum of its proper divisors (4483).

137981 is an equidigital number, since it uses as much as digits as its factorization.

137981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4482.

The product of its digits is 1512, while the sum is 29.

The square root of 137981 is about 371.4579383995. The cubic root of 137981 is about 51.6741207883.

The spelling of 137981 in words is "one hundred thirty-seven thousand, nine hundred eighty-one".