138531951 has 20 divisors (see below), whose sum is σ = 209572000. Its totient is φ = 91181376.

The previous prime is 138531931. The next prime is 138531977. The reversal of 138531951 is 159135831.

138531951 is a `hidden beast` number, since 1 + 38 + 531 + 95 + 1 = 666.

It is not a de Polignac number, because 138531951 - 2⁵ = 138531919 is a prime.

It is a super-2 number, since 2×138531951² = 38382202895732802, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138531931) 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 19 ways as a sum of consecutive naturals, for example, 4426 + ... + 17223.

It is an arithmetic number, because the mean of its divisors is an integer number (10478600).

Almost surely, 2^138531951 is an apocalyptic number.

138531951 is a deficient number, since it is larger than the sum of its proper divisors (71040049).

138531951 is an equidigital number, since it uses as much as digits as its factorization.

138531951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21740 (or 21731 counting only the distinct ones).

The product of its digits is 16200, while the sum is 36.

The square root of 138531951 is about 11769.9596855724. The cubic root of 138531951 is about 517.4280681369.

The spelling of 138531951 in words is "one hundred thirty-eight million, five hundred thirty-one thousand, nine hundred fifty-one".