139165981 has 4 divisors (see below), whose sum is σ = 140543964. Its totient is φ = 137788000.

The previous prime is 139165973. The next prime is 139165987. The reversal of 139165981 is 189561931.

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 60684100 + 78481881 = 7790^2 + 8859^2 .

It is a cyclic number.

It is not a de Polignac number, because 139165981 - 2³ = 139165973 is a prime.

It is a super-2 number, since 2×139165981² = 38734340535384722, 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 (139165987) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 688840 + ... + 689041.

It is an arithmetic number, because the mean of its divisors is an integer number (35135991).

Almost surely, 2^139165981 is an apocalyptic number.

It is an amenable number.

139165981 is a deficient number, since it is larger than the sum of its proper divisors (1377983).

139165981 is a wasteful number, since it uses less digits than its factorization.

139165981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1377982.

The product of its digits is 58320, while the sum is 43.

The square root of 139165981 is about 11796.8631847623. The cubic root of 139165981 is about 518.2162513946.

The spelling of 139165981 in words is "one hundred thirty-nine million, one hundred sixty-five thousand, nine hundred eighty-one".