1555649989 has 2 divisors, whose sum is σ = 1555649990. Its totient is φ = 1555649988.

The previous prime is 1555649959. The next prime is 1555650017. The reversal of 1555649989 is 9899465551.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1074725089 + 480924900 = 32783^2 + 21930^2 .

It is a cyclic number.

It is not a de Polignac number, because 1555649989 - 2⁷ = 1555649861 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1555649959) 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, 777824994 + 777824995.

It is an arithmetic number, because the mean of its divisors is an integer number (777824995).

Almost surely, 2^1555649989 is an apocalyptic number.

It is an amenable number.

1555649989 is a deficient number, since it is larger than the sum of its proper divisors (1).

1555649989 is an equidigital number, since it uses as much as digits as its factorization.

1555649989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17496000, while the sum is 61.

The square root of 1555649989 is about 39441.7290315726. The cubic root of 1555649989 is about 1158.6989944760.

The spelling of 1555649989 in words is "one billion, five hundred fifty-five million, six hundred forty-nine thousand, nine hundred eighty-nine".