1555055221 has 2 divisors, whose sum is σ = 1555055222. Its totient is φ = 1555055220.

The previous prime is 1555055191. The next prime is 1555055237. The reversal of 1555055221 is 1225505551.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1529904996 + 25150225 = 39114^2 + 5015^2 .

It is an emirp because it is prime and its reverse (1225505551) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1555055221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1555055261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 777527610 + 777527611.

It is an arithmetic number, because the mean of its divisors is an integer number (777527611).

Almost surely, 2^1555055221 is an apocalyptic number.

It is an amenable number.

1555055221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1555055221 is an equidigital number, since it uses as much as digits as its factorization.

1555055221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12500, while the sum is 31.

The square root of 1555055221 is about 39434.1884790343. The cubic root of 1555055221 is about 1158.5513080994.

The spelling of 1555055221 in words is "one billion, five hundred fifty-five million, fifty-five thousand, two hundred twenty-one".