155413721 has 2 divisors, whose sum is σ = 155413722. Its totient is φ = 155413720.

The previous prime is 155413681. The next prime is 155413733. The reversal of 155413721 is 127314551.

155413721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 104448400 + 50965321 = 10220^2 + 7139^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-155413721 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (155413751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77706860 + 77706861.

It is an arithmetic number, because the mean of its divisors is an integer number (77706861).

Almost surely, 2^155413721 is an apocalyptic number.

It is an amenable number.

155413721 is a deficient number, since it is larger than the sum of its proper divisors (1).

155413721 is an equidigital number, since it uses as much as digits as its factorization.

155413721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4200, while the sum is 29.

The square root of 155413721 is about 12466.5039606138. The cubic root of 155413721 is about 537.6460418736.

The spelling of 155413721 in words is "one hundred fifty-five million, four hundred thirteen thousand, seven hundred twenty-one".