121565721061 has 2 divisors, whose sum is σ = 121565721062. Its totient is φ = 121565721060.

The previous prime is 121565721029. The next prime is 121565721083. The reversal of 121565721061 is 160127565121.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 118205316100 + 3360404961 = 343810^2 + 57969^2 .

It is a cyclic number.

It is not a de Polignac number, because 121565721061 - 2⁵ = 121565721029 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 121565721061.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (121565727061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 60782860530 + 60782860531.

It is an arithmetic number, because the mean of its divisors is an integer number (60782860531).

Almost surely, 2^121565721061 is an apocalyptic number.

It is an amenable number.

121565721061 is a deficient number, since it is larger than the sum of its proper divisors (1).

121565721061 is an equidigital number, since it uses as much as digits as its factorization.

121565721061 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 25200, while the sum is 37.

The spelling of 121565721061 in words is "one hundred twenty-one billion, five hundred sixty-five million, seven hundred twenty-one thousand, sixty-one".