180687721 has 4 divisors (see below), whose sum is σ = 180821844. Its totient is φ = 180553600.

The previous prime is 180687709. The next prime is 180687737. The reversal of 180687721 is 127786081.

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 62726400 + 117961321 = 7920^2 + 10861^2 .

It is a cyclic number.

It is not a de Polignac number, because 180687721 - 2⁷ = 180687593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (180657721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65020 + ... + 67741.

It is an arithmetic number, because the mean of its divisors is an integer number (45205461).

Almost surely, 2^180687721 is an apocalyptic number.

It is an amenable number.

180687721 is a deficient number, since it is larger than the sum of its proper divisors (134123).

180687721 is a wasteful number, since it uses less digits than its factorization.

180687721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 134122.

The product of its (nonzero) digits is 37632, while the sum is 40.

The square root of 180687721 is about 13442.0132792674. The cubic root of 180687721 is about 565.3397815235.

The spelling of 180687721 in words is "one hundred eighty million, six hundred eighty-seven thousand, seven hundred twenty-one".