129284112721 has 3 divisors (see below), whose sum is σ = 129284472283. Its totient is φ = 129283753160.

The previous prime is 129284112709. The next prime is 129284112731. The reversal of 129284112721 is 127211482921.

It is a happy number.

The square root of 129284112721 is 359561.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 127211482921 = 305927 ⋅415823.

It can be written as a sum of positive squares in only one way, i.e., 19723112721 + 109561000000 = 140439^2 + 331000^2 .

It is not a de Polignac number, because 129284112721 - 2⁵ = 129284112689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (129284112731) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 179781 + ... + 539341.

Almost surely, 2^129284112721 is an apocalyptic number.

129284112721 is the 359561-st square number.

129284112721 is the 179781-st centered octagonal number.

It is an amenable number.

129284112721 is a deficient number, since it is larger than the sum of its proper divisors (359562).

129284112721 is an frugal number, since it uses more digits than its factorization.

129284112721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 719122 (or 359561 counting only the distinct ones).

The product of its digits is 32256, while the sum is 40.

The spelling of 129284112721 in words is "one hundred twenty-nine billion, two hundred eighty-four million, one hundred twelve thousand, seven hundred twenty-one".