138971691 has 6 divisors (see below), whose sum is σ = 200736900. Its totient is φ = 92647788.

The previous prime is 138971689. The next prime is 138971699. The reversal of 138971691 is 196179831.

It is not a de Polignac number, because 138971691 - 2¹ = 138971689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (138971699) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 7720641 + ... + 7720658.

It is an arithmetic number, because the mean of its divisors is an integer number (33456150).

Almost surely, 2^138971691 is an apocalyptic number.

138971691 is a deficient number, since it is larger than the sum of its proper divisors (61765209).

138971691 is a wasteful number, since it uses less digits than its factorization.

138971691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15441305 (or 15441302 counting only the distinct ones).

The product of its digits is 81648, while the sum is 45.

The square root of 138971691 is about 11788.6254923973. The cubic root of 138971691 is about 517.9749780453.

The spelling of 138971691 in words is "one hundred thirty-eight million, nine hundred seventy-one thousand, six hundred ninety-one".