3129171721 has 15 divisors (see below), whose sum is σ = 3400199313. Its totient is φ = 2879739720.

The previous prime is 3129171709. The next prime is 3129171739. The reversal of 3129171721 is 1271719213.

The square root of 3129171721 is 55939.

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

3129171721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 1551493321 + 1577678400 = 39389^2 + 39720^2 .

It is not a de Polignac number, because 3129171721 - 2²¹ = 3127074569 is a prime.

It is a super-2 number, since 2×3129171721² = 19583431319012203682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3129171421) by changing a digit.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 9453526 + ... + 9453856.

Almost surely, 2^3129171721 is an apocalyptic number.

3129171721 is the 55939-th square number.

3129171721 is the 27970-th centered octagonal number.

It is an amenable number.

3129171721 is a deficient number, since it is larger than the sum of its proper divisors (271027592).

3129171721 is an frugal number, since it uses more digits than its factorization.

3129171721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 714 (or 344 counting only the distinct ones).

The product of its digits is 5292, while the sum is 34.

The cubic root of 3129171721 is about 1462.6591497588.

The spelling of 3129171721 in words is "three billion, one hundred twenty-nine million, one hundred seventy-one thousand, seven hundred twenty-one".