180128721 has 8 divisors (see below), whose sum is σ = 252812320. Its totient is φ = 113765472.

The previous prime is 180128717. The next prime is 180128731. The reversal of 180128721 is 127821081.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 180128721 - 2² = 180128717 is a prime.

It is a super-2 number, since 2×180128721² = 64892712258191682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (180128701) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1580020 + ... + 1580133.

It is an arithmetic number, because the mean of its divisors is an integer number (31601540).

Almost surely, 2^180128721 is an apocalyptic number.

It is an amenable number.

180128721 is a deficient number, since it is larger than the sum of its proper divisors (72683599).

180128721 is a wasteful number, since it uses less digits than its factorization.

180128721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3160175.

The product of its (nonzero) digits is 1792, while the sum is 30.

The square root of 180128721 is about 13421.2041561106. The cubic root of 180128721 is about 564.7561753685.

The spelling of 180128721 in words is "one hundred eighty million, one hundred twenty-eight thousand, seven hundred twenty-one".