139665661 has 4 divisors (see below), whose sum is σ = 141955324. Its totient is φ = 137376000.

The previous prime is 139665649. The next prime is 139665667. The reversal of 139665661 is 166566931.

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 64080025 + 75585636 = 8005^2 + 8694^2 .

It is a cyclic number.

It is not a de Polignac number, because 139665661 - 2⁵ = 139665629 is a prime.

It is a super-3 number, since 3×139665661³ (a number of 25 digits) contains 333 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 (139665667) 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 3 ways as a sum of consecutive naturals, for example, 1144740 + ... + 1144861.

It is an arithmetic number, because the mean of its divisors is an integer number (35488831).

Almost surely, 2^139665661 is an apocalyptic number.

It is an amenable number.

139665661 is a deficient number, since it is larger than the sum of its proper divisors (2289663).

139665661 is an equidigital number, since it uses as much as digits as its factorization.

139665661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2289662.

The product of its digits is 174960, while the sum is 43.

The square root of 139665661 is about 11818.0227195585. The cubic root of 139665661 is about 518.8357346854.

The spelling of 139665661 in words is "one hundred thirty-nine million, six hundred sixty-five thousand, six hundred sixty-one".