187813321 has 2 divisors, whose sum is σ = 187813322. Its totient is φ = 187813320.

The previous prime is 187813319. The next prime is 187813337. The reversal of 187813321 is 123318781.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 94478400 + 93334921 = 9720^2 + 9661^2 .

It is an emirp because it is prime and its reverse (123318781) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 187813321 - 2¹ = 187813319 is a prime.

Together with 187813319, it forms a pair of twin primes.

It is the 13705-th Hogben number.

It is not a weakly prime, because it can be changed into another prime (187813361) by changing a digit.

It is a nontrivial repunit in base 13704.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 93906660 + 93906661.

It is an arithmetic number, because the mean of its divisors is an integer number (93906661).

Almost surely, 2^187813321 is an apocalyptic number.

It is an amenable number.

187813321 is a deficient number, since it is larger than the sum of its proper divisors (1).

187813321 is an equidigital number, since it uses as much as digits as its factorization.

187813321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8064, while the sum is 34.

The square root of 187813321 is about 13704.5000273633. The cubic root of 187813321 is about 572.6757554240.

The spelling of 187813321 in words is "one hundred eighty-seven million, eight hundred thirteen thousand, three hundred twenty-one".