155520221497 has 2 divisors, whose sum is σ = 155520221498. Its totient is φ = 155520221496.

The previous prime is 155520221477. The next prime is 155520221573. The reversal of 155520221497 is 794122025551.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 147689564416 + 7830657081 = 384304^2 + 88491^2 .

It is an emirp because it is prime and its reverse (794122025551) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 155520221497 - 2⁷ = 155520221369 is a prime.

It is not a weakly prime, because it can be changed into another prime (155520221477) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77760110748 + 77760110749.

It is an arithmetic number, because the mean of its divisors is an integer number (77760110749).

Almost surely, 2^155520221497 is an apocalyptic number.

It is an amenable number.

155520221497 is a deficient number, since it is larger than the sum of its proper divisors (1).

155520221497 is an equidigital number, since it uses as much as digits as its factorization.

155520221497 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 252000, while the sum is 43.

The spelling of 155520221497 in words is "one hundred fifty-five billion, five hundred twenty million, two hundred twenty-one thousand, four hundred ninety-seven".