201509643121 has 4 divisors (see below), whose sum is σ = 201715897572. Its totient is φ = 201303388672.

The previous prime is 201509643103. The next prime is 201509643143. The reversal of 201509643121 is 121346905102.

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

It can be written as a sum of positive squares in 2 ways, for example, as 124636535521 + 76873107600 = 353039^2 + 277260^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-201509643121 is a prime.

It is a super-2 number, since 2×201509643121² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (201509643221) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 103125760 + ... + 103127713.

It is an arithmetic number, because the mean of its divisors is an integer number (50428974393).

Almost surely, 2^201509643121 is an apocalyptic number.

It is an amenable number.

201509643121 is a deficient number, since it is larger than the sum of its proper divisors (206254451).

201509643121 is an equidigital number, since it uses as much as digits as its factorization.

201509643121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 206254450.

The product of its (nonzero) digits is 12960, while the sum is 34.

The spelling of 201509643121 in words is "two hundred one billion, five hundred nine million, six hundred forty-three thousand, one hundred twenty-one".