155040721921 has 2 divisors, whose sum is σ = 155040721922. Its totient is φ = 155040721920.

The previous prime is 155040721907. The next prime is 155040721937. The reversal of 155040721921 is 129127040551.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 107226777025 + 47813944896 = 327455^2 + 218664^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-155040721921 is a prime.

It is a super-3 number, since 3×155040721921³ (a number of 35 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (155040721961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77520360960 + 77520360961.

It is an arithmetic number, because the mean of its divisors is an integer number (77520360961).

Almost surely, 2^155040721921 is an apocalyptic number.

It is an amenable number.

155040721921 is a deficient number, since it is larger than the sum of its proper divisors (1).

155040721921 is an equidigital number, since it uses as much as digits as its factorization.

155040721921 is an odious number, because the sum of its binary digits is odd.

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

The spelling of 155040721921 in words is "one hundred fifty-five billion, forty million, seven hundred twenty-one thousand, nine hundred twenty-one".