138992661 has 6 divisors (see below), whose sum is σ = 200767190. Its totient is φ = 92661768.

The previous prime is 138992647. The next prime is 138992699. The reversal of 138992661 is 166299831.

It is a happy number.

138992661 is a `hidden beast` number, since 1 + 389 + 9 + 266 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 79548561 + 59444100 = 8919^2 + 7710^2 .

It is not a de Polignac number, because 138992661 - 2⁷ = 138992533 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138992761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 7721806 + ... + 7721823.

Almost surely, 2^138992661 is an apocalyptic number.

It is an amenable number.

138992661 is a deficient number, since it is larger than the sum of its proper divisors (61774529).

138992661 is a wasteful number, since it uses less digits than its factorization.

138992661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15443635 (or 15443632 counting only the distinct ones).

The product of its digits is 139968, while the sum is 45.

The square root of 138992661 is about 11789.5148755154. The cubic root of 138992661 is about 518.0010298474.

The spelling of 138992661 in words is "one hundred thirty-eight million, nine hundred ninety-two thousand, six hundred sixty-one".