129985981 has 4 divisors (see below), whose sum is σ = 130008832. Its totient is φ = 129963132.

The previous prime is 129985979. The next prime is 129985991. The reversal of 129985981 is 189589921.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 189589921 = 7109 ⋅26669.

It is a cyclic number.

It is not a de Polignac number, because 129985981 - 2¹ = 129985979 is a prime.

It is a super-2 number, since 2×129985981² = 33792710513064722, 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 (129985901) 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, 4606 + ... + 16768.

It is an arithmetic number, because the mean of its divisors is an integer number (32502208).

Almost surely, 2^129985981 is an apocalyptic number.

It is an amenable number.

129985981 is a deficient number, since it is larger than the sum of its proper divisors (22851).

129985981 is a wasteful number, since it uses less digits than its factorization.

129985981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22850.

The product of its digits is 466560, while the sum is 52.

The square root of 129985981 is about 11401.1394605978. The cubic root of 129985981 is about 506.5614916636.

The spelling of 129985981 in words is "one hundred twenty-nine million, nine hundred eighty-five thousand, nine hundred eighty-one".