139243691 has 4 divisors (see below), whose sum is σ = 143007072. Its totient is φ = 135480312.

The previous prime is 139243673. The next prime is 139243693. The reversal of 139243691 is 196342931.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 196342931 = 131 ⋅1498801.

It is a cyclic number.

It is not a de Polignac number, because 139243691 - 2²⁶ = 72134827 is a prime.

It is not an unprimeable number, because it can be changed into a prime (139243693) 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, 1881635 + ... + 1881708.

It is an arithmetic number, because the mean of its divisors is an integer number (35751768).

Almost surely, 2^139243691 is an apocalyptic number.

139243691 is a deficient number, since it is larger than the sum of its proper divisors (3763381).

139243691 is an equidigital number, since it uses as much as digits as its factorization.

139243691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3763380.

The product of its digits is 34992, while the sum is 38.

The square root of 139243691 is about 11800.1563972686. The cubic root of 139243691 is about 518.3126904124.

The spelling of 139243691 in words is "one hundred thirty-nine million, two hundred forty-three thousand, six hundred ninety-one".