201511209961 has 2 divisors, whose sum is σ = 201511209962. Its totient is φ = 201511209960.

The previous prime is 201511209959. The next prime is 201511209989. The reversal of 201511209961 is 169902115102.

201511209961 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 201471708736 + 39501225 = 448856^2 + 6285^2 .

It is a cyclic number.

It is not a de Polignac number, because 201511209961 - 2¹ = 201511209959 is a prime.

Together with 201511209959, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 201511209961.

It is not a weakly prime, because it can be changed into another prime (201511209161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 100755604980 + 100755604981.

It is an arithmetic number, because the mean of its divisors is an integer number (100755604981).

Almost surely, 2^201511209961 is an apocalyptic number.

It is an amenable number.

201511209961 is a deficient number, since it is larger than the sum of its proper divisors (1).

201511209961 is an equidigital number, since it uses as much as digits as its factorization.

201511209961 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9720, while the sum is 37.

The spelling of 201511209961 in words is "two hundred one billion, five hundred eleven million, two hundred nine thousand, nine hundred sixty-one".