138787681 has 4 divisors (see below), whose sum is σ = 144821952. Its totient is φ = 132753412.

The previous prime is 138787679. The next prime is 138787687. The reversal of 138787681 is 186787831.

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.

It is a cyclic number.

It is not a de Polignac number, because 138787681 - 2¹ = 138787679 is a prime.

It is a super-2 number, since 2×138787681² = 38524040794715522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138787687) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3017101 + ... + 3017146.

It is an arithmetic number, because the mean of its divisors is an integer number (36205488).

Almost surely, 2^138787681 is an apocalyptic number.

It is an amenable number.

138787681 is a deficient number, since it is larger than the sum of its proper divisors (6034271).

138787681 is an equidigital number, since it uses as much as digits as its factorization.

138787681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6034270.

The product of its digits is 451584, while the sum is 49.

The square root of 138787681 is about 11780.8183501826. The cubic root of 138787681 is about 517.7462631820.

The spelling of 138787681 in words is "one hundred thirty-eight million, seven hundred eighty-seven thousand, six hundred eighty-one".