155123237277721 has 2 divisors, whose sum is σ = 155123237277722. Its totient is φ = 155123237277720.

The previous prime is 155123237277689. The next prime is 155123237277727. The reversal of 155123237277721 is 127772732321551.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 129768094896400 + 25355142381321 = 11391580^2 + 5035389^2 .

It is a cyclic number.

It is not a de Polignac number, because 155123237277721 - 2⁵ = 155123237277689 is a prime.

It is not a weakly prime, because it can be changed into another prime (155123237277727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77561618638860 + 77561618638861.

It is an arithmetic number, because the mean of its divisors is an integer number (77561618638861).

Almost surely, 2^{155123237277721} is an apocalyptic number.

It is an amenable number.

155123237277721 is a deficient number, since it is larger than the sum of its proper divisors (1).

155123237277721 is an equidigital number, since it uses as much as digits as its factorization.

155123237277721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8643600, while the sum is 55.

The spelling of 155123237277721 in words is "one hundred fifty-five trillion, one hundred twenty-three billion, two hundred thirty-seven million, two hundred seventy-seven thousand, seven hundred twenty-one".