155243521 has 2 divisors, whose sum is σ = 155243522. Its totient is φ = 155243520.

The previous prime is 155243503. The next prime is 155243531. The reversal of 155243521 is 125342551.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 135396496 + 19847025 = 11636^2 + 4455^2 .

It is a cyclic number.

It is not a de Polignac number, because 155243521 - 2⁷ = 155243393 is a prime.

It is a super-5 number, since 5×155243521⁵ (a number of 42 digits) contains 55555 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 155243521.

It is not a weakly prime, because it can be changed into another prime (155243531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77621760 + 77621761.

It is an arithmetic number, because the mean of its divisors is an integer number (77621761).

Almost surely, 2^155243521 is an apocalyptic number.

It is an amenable number.

155243521 is a deficient number, since it is larger than the sum of its proper divisors (1).

155243521 is an equidigital number, since it uses as much as digits as its factorization.

155243521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6000, while the sum is 28.

The square root of 155243521 is about 12459.6757983505. The cubic root of 155243521 is about 537.4497040372.

The spelling of 155243521 in words is "one hundred fifty-five million, two hundred forty-three thousand, five hundred twenty-one".