1555855361 has 2 divisors, whose sum is σ = 1555855362. Its totient is φ = 1555855360.

The previous prime is 1555855319. The next prime is 1555855387. The reversal of 1555855361 is 1635585551.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 831976336 + 723879025 = 28844^2 + 26905^2 .

It is a cyclic number.

It is not a de Polignac number, because 1555855361 - 2⁶ = 1555855297 is a prime.

It is not a weakly prime, because it can be changed into another prime (1555855391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 777927680 + 777927681.

It is an arithmetic number, because the mean of its divisors is an integer number (777927681).

Almost surely, 2^1555855361 is an apocalyptic number.

It is an amenable number.

1555855361 is a deficient number, since it is larger than the sum of its proper divisors (1).

1555855361 is an equidigital number, since it uses as much as digits as its factorization.

1555855361 is an evil number, because the sum of its binary digits is even.

The product of its digits is 450000, while the sum is 44.

The square root of 1555855361 is about 39444.3324319223. The cubic root of 1555855361 is about 1158.7499814933.

The spelling of 1555855361 in words is "one billion, five hundred fifty-five million, eight hundred fifty-five thousand, three hundred sixty-one".