201021987 has 4 divisors (see below), whose sum is σ = 268029320. Its totient is φ = 134014656.

The previous prime is 201021973. The next prime is 201022007. The reversal of 201021987 is 789120102.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 201021987 - 2⁷ = 201021859 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (201021917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 33503662 + ... + 33503667.

It is an arithmetic number, because the mean of its divisors is an integer number (67007330).

Almost surely, 2^201021987 is an apocalyptic number.

201021987 is a deficient number, since it is larger than the sum of its proper divisors (67007333).

201021987 is an equidigital number, since it uses as much as digits as its factorization.

201021987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67007332.

The product of its (nonzero) digits is 2016, while the sum is 30.

The square root of 201021987 is about 14178.2222792563. Note that the first 4 decimals coincide. The cubic root of 201021987 is about 585.7979584749.

The spelling of 201021987 in words is "two hundred one million, twenty-one thousand, nine hundred eighty-seven".