155315521 has 2 divisors, whose sum is σ = 155315522. Its totient is φ = 155315520.

The previous prime is 155315513. The next prime is 155315533. The reversal of 155315521 is 125513551.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 143065521 + 12250000 = 11961^2 + 3500^2 .

It is an emirp because it is prime and its reverse (125513551) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 155315521 - 2³ = 155315513 is a prime.

It is a super-2 number, since 2×155315521² = 48245822127002882, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 155315521.

It is not a weakly prime, because it can be changed into another prime (155315221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77657760 + 77657761.

It is an arithmetic number, because the mean of its divisors is an integer number (77657761).

Almost surely, 2^155315521 is an apocalyptic number.

It is an amenable number.

155315521 is a deficient number, since it is larger than the sum of its proper divisors (1).

155315521 is an equidigital number, since it uses as much as digits as its factorization.

155315521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3750, while the sum is 28.

The square root of 155315521 is about 12462.5647841847. The cubic root of 155315521 is about 537.5327786752.

The spelling of 155315521 in words is "one hundred fifty-five million, three hundred fifteen thousand, five hundred twenty-one".