138669531 has 64 divisors (see below), whose sum is σ = 252650496. Its totient is φ = 65318400.

The previous prime is 138669523. The next prime is 138669547. The reversal of 138669531 is 135966831.

It is a happy number.

138669531 is a nontrivial binomial coefficient, being equal to C(16654, 2).

It is not a de Polignac number, because 138669531 - 2³ = 138669523 is a prime.

It is a super-2 number, since 2×138669531² = 38458477655519922, which contains 22 as substring.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (138669131) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 182805 + ... + 183561.

It is an arithmetic number, because the mean of its divisors is an integer number (3947664).

Almost surely, 2^138669531 is an apocalyptic number.

138669531 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

138669531 is the 16653-rd triangular number and also the 8327-th hexagonal number.

138669531 is a deficient number, since it is larger than the sum of its proper divisors (113980965).

138669531 is a wasteful number, since it uses less digits than its factorization.

138669531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 852.

The product of its digits is 116640, while the sum is 42.

The square root of 138669531 is about 11775.8027751827. The cubic root of 138669531 is about 517.5993022815.

The spelling of 138669531 in words is "one hundred thirty-eight million, six hundred sixty-nine thousand, five hundred thirty-one".