1555551989 has 2 divisors, whose sum is σ = 1555551990. Its totient is φ = 1555551988.

The previous prime is 1555551953. The next prime is 1555552001. The reversal of 1555551989 is 9891555551.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 870840100 + 684711889 = 29510^2 + 26167^2 .

It is a cyclic number.

It is not a de Polignac number, because 1555551989 - 2⁸ = 1555551733 is a prime.

It is a super-2 number, since 2×1555551989² = 4839483980963712242, 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 1555551989.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1555551929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 777775994 + 777775995.

It is an arithmetic number, because the mean of its divisors is an integer number (777775995).

Almost surely, 2^1555551989 is an apocalyptic number.

It is an amenable number.

1555551989 is a deficient number, since it is larger than the sum of its proper divisors (1).

1555551989 is an equidigital number, since it uses as much as digits as its factorization.

1555551989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2025000, while the sum is 53.

The square root of 1555551989 is about 39440.4866729608. The cubic root of 1555551989 is about 1158.6746627632.

The spelling of 1555551989 in words is "one billion, five hundred fifty-five million, five hundred fifty-one thousand, nine hundred eighty-nine".