187540721 has 2 divisors, whose sum is σ = 187540722. Its totient is φ = 187540720.

The previous prime is 187540699. The next prime is 187540729. The reversal of 187540721 is 127045781.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 185940496 + 1600225 = 13636^2 + 1265^2 .

It is a cyclic number.

It is not a de Polignac number, because 187540721 - 2¹⁸ = 187278577 is a prime.

It is not a weakly prime, because it can be changed into another prime (187540729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 93770360 + 93770361.

It is an arithmetic number, because the mean of its divisors is an integer number (93770361).

Almost surely, 2^187540721 is an apocalyptic number.

It is an amenable number.

187540721 is a deficient number, since it is larger than the sum of its proper divisors (1).

187540721 is an equidigital number, since it uses as much as digits as its factorization.

187540721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15680, while the sum is 35.

The square root of 187540721 is about 13694.5507775903. The cubic root of 187540721 is about 572.3985528629.

The spelling of 187540721 in words is "one hundred eighty-seven million, five hundred forty thousand, seven hundred twenty-one".