138440081 has 8 divisors (see below), whose sum is σ = 151903080. Its totient is φ = 125379072.

The previous prime is 138440077. The next prime is 138440083. The reversal of 138440081 is 180044831.

It can be written as a sum of positive squares in 4 ways, for example, as 53523856 + 84916225 = 7316^2 + 9215^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 138440081 - 2² = 138440077 is a prime.

It is a super-2 number, since 2×138440081² = 38331312054573122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138440083) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 99776 + ... + 101153.

It is an arithmetic number, because the mean of its divisors is an integer number (18987885).

Almost surely, 2^138440081 is an apocalyptic number.

It is an amenable number.

138440081 is a deficient number, since it is larger than the sum of its proper divisors (13462999).

138440081 is a wasteful number, since it uses less digits than its factorization.

138440081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 200995.

The product of its (nonzero) digits is 3072, while the sum is 29.

The square root of 138440081 is about 11766.0563061716. The cubic root of 138440081 is about 517.3136622103.

The spelling of 138440081 in words is "one hundred thirty-eight million, four hundred forty thousand, eighty-one".