139691 has 4 divisors (see below), whose sum is σ = 140712. Its totient is φ = 138672.

The previous prime is 139681. The next prime is 139697. The reversal of 139691 is 196931.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 139691 - 2⁶ = 139627 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (139697) 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, 266 + ... + 591.

It is an arithmetic number, because the mean of its divisors is an integer number (35178).

2¹³⁹⁶⁹¹ is an apocalyptic number.

139691 is a deficient number, since it is larger than the sum of its proper divisors (1021).

139691 is an equidigital number, since it uses as much as digits as its factorization.

139691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1020.

The product of its digits is 1458, while the sum is 29.

The square root of 139691 is about 373.7525919643. The cubic root of 139691 is about 51.8867109574.

The spelling of 139691 in words is "one hundred thirty-nine thousand, six hundred ninety-one".