1988409505 has 16 divisors (see below), whose sum is σ = 2613571920. Its totient is φ = 1445527552.

The previous prime is 1988409491. The next prime is 1988409517. The reversal of 1988409505 is 5059048891.

It can be written as a sum of positive squares in 8 ways, for example, as 7447441 + 1980962064 = 2729^2 + 44508^2 .

It is a cyclic number.

It is not a de Polignac number, because 1988409505 - 2⁷ = 1988409377 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 400864 + ... + 405793.

It is an arithmetic number, because the mean of its divisors is an integer number (163348245).

Almost surely, 2^1988409505 is an apocalyptic number.

It is an amenable number.

1988409505 is a deficient number, since it is larger than the sum of its proper divisors (625162415).

1988409505 is a wasteful number, since it uses less digits than its factorization.

1988409505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 806708.

The product of its (nonzero) digits is 518400, while the sum is 49.

The square root of 1988409505 is about 44591.5855851751. The cubic root of 1988409505 is about 1257.4824816703.

The spelling of 1988409505 in words is "one billion, nine hundred eighty-eight million, four hundred nine thousand, five hundred five".