138642261 has 16 divisors (see below), whose sum is σ = 191132160. Its totient is φ = 89300160.

The previous prime is 138642253. The next prime is 138642269. The reversal of 138642261 is 162246831.

It is an interprime number because it is at equal distance from previous prime (138642253) and next prime (138642269).

It is not a de Polignac number, because 138642261 - 2³ = 138642253 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138642269) 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 15 ways as a sum of consecutive naturals, for example, 112195 + ... + 113423.

It is an arithmetic number, because the mean of its divisors is an integer number (11945760).

Almost surely, 2^138642261 is an apocalyptic number.

It is an amenable number.

138642261 is a deficient number, since it is larger than the sum of its proper divisors (52489899).

138642261 is a wasteful number, since it uses less digits than its factorization.

138642261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2476.

The product of its digits is 13824, while the sum is 33.

The square root of 138642261 is about 11774.6448354080. The cubic root of 138642261 is about 517.5653706307.

The spelling of 138642261 in words is "one hundred thirty-eight million, six hundred forty-two thousand, two hundred sixty-one".