187455721 has 2 divisors, whose sum is σ = 187455722. Its totient is φ = 187455720.

The previous prime is 187455679. The next prime is 187455733. The reversal of 187455721 is 127554781.

187455721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 100220121 + 87235600 = 10011^2 + 9340^2 .

It is an emirp because it is prime and its reverse (127554781) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 187455721 - 2¹³ = 187447529 is a prime.

It is not a weakly prime, because it can be changed into another prime (187455421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 93727860 + 93727861.

It is an arithmetic number, because the mean of its divisors is an integer number (93727861).

Almost surely, 2^187455721 is an apocalyptic number.

It is an amenable number.

187455721 is a deficient number, since it is larger than the sum of its proper divisors (1).

187455721 is an equidigital number, since it uses as much as digits as its factorization.

187455721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 78400, while the sum is 40.

The square root of 187455721 is about 13691.4470016869. The cubic root of 187455721 is about 572.3120627945.

The spelling of 187455721 in words is "one hundred eighty-seven million, four hundred fifty-five thousand, seven hundred twenty-one".