139781 has 4 divisors (see below), whose sum is σ = 141132. Its totient is φ = 138432.

The previous prime is 139759. The next prime is 139787. The reversal of 139781 is 187931.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 43681 + 96100 = 209^2 + 310^2 .

It is a cyclic number.

It is not a de Polignac number, because 139781 - 2¹⁴ = 123397 is a prime.

It is a super-2 number, since 2×139781² = 39077455922, 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 139781.

It is not an unprimeable number, because it can be changed into a prime (139787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 506 + ... + 731.

It is an arithmetic number, because the mean of its divisors is an integer number (35283).

2¹³⁹⁷⁸¹ is an apocalyptic number.

It is an amenable number.

139781 is a deficient number, since it is larger than the sum of its proper divisors (1351).

139781 is a wasteful number, since it uses less digits than its factorization.

139781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1350.

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

The square root of 139781 is about 373.8729730804. The cubic root of 139781 is about 51.8978517407.

The spelling of 139781 in words is "one hundred thirty-nine thousand, seven hundred eighty-one".