187212721 has 8 divisors (see below), whose sum is σ = 201475944. Its totient is φ = 173310720.

The previous prime is 187212679. The next prime is 187212731. The reversal of 187212721 is 127212781.

It can be written as a sum of positive squares in 4 ways, for example, as 20802721 + 166410000 = 4561^2 + 12900^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 187212721 - 2⁷ = 187212593 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (187212731) 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 7 ways as a sum of consecutive naturals, for example, 89230 + ... + 91303.

It is an arithmetic number, because the mean of its divisors is an integer number (25184493).

Almost surely, 2^187212721 is an apocalyptic number.

It is an amenable number.

187212721 is a deficient number, since it is larger than the sum of its proper divisors (14263223).

187212721 is a wasteful number, since it uses less digits than its factorization.

187212721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 180611.

The product of its digits is 3136, while the sum is 31.

The square root of 187212721 is about 13682.5699705867. The cubic root of 187212721 is about 572.0646586483.

The spelling of 187212721 in words is "one hundred eighty-seven million, two hundred twelve thousand, seven hundred twenty-one".