187988021 has 8 divisors (see below), whose sum is σ = 202566840. Its totient is φ = 173426112.

The previous prime is 187988011. The next prime is 187988029. The reversal of 187988021 is 120889781.

187988021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 7623121 + 180364900 = 2761^2 + 13430^2 .

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 187988021 - 2¹⁸ = 187725877 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (187988029) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28031 + ... + 34083.

It is an arithmetic number, because the mean of its divisors is an integer number (25320855).

Almost surely, 2^187988021 is an apocalyptic number.

It is an amenable number.

187988021 is a deficient number, since it is larger than the sum of its proper divisors (14578819).

187988021 is a wasteful number, since it uses less digits than its factorization.

187988021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8455.

The product of its (nonzero) digits is 64512, while the sum is 44.

The square root of 187988021 is about 13710.8723646601. The cubic root of 187988021 is about 572.8532640437.

The spelling of 187988021 in words is "one hundred eighty-seven million, nine hundred eighty-eight thousand, twenty-one".