138971537 has 4 divisors (see below), whose sum is σ = 139154916. Its totient is φ = 138788160.

The previous prime is 138971531. The next prime is 138971551. The reversal of 138971537 is 735179831.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 46022656 + 92948881 = 6784^2 + 9641^2 .

It is a cyclic number.

It is not a de Polignac number, because 138971537 - 2⁶ = 138971473 is a prime.

It is a super-2 number, since 2×138971537² = 38626176192284738, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138971531) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 90548 + ... + 92069.

It is an arithmetic number, because the mean of its divisors is an integer number (34788729).

Almost surely, 2^138971537 is an apocalyptic number.

It is an amenable number.

138971537 is a deficient number, since it is larger than the sum of its proper divisors (183379).

138971537 is an equidigital number, since it uses as much as digits as its factorization.

138971537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 183378.

The product of its digits is 158760, while the sum is 44.

The square root of 138971537 is about 11788.6189606756. The cubic root of 138971537 is about 517.9747867157.

The spelling of 138971537 in words is "one hundred thirty-eight million, nine hundred seventy-one thousand, five hundred thirty-seven".