1687538989 has 2 divisors, whose sum is σ = 1687538990. Its totient is φ = 1687538988.

The previous prime is 1687538977. The next prime is 1687539019. The reversal of 1687538989 is 9898357861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 896523364 + 791015625 = 29942^2 + 28125^2 .

It is a cyclic number.

It is not a de Polignac number, because 1687538989 - 2⁷ = 1687538861 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1687538989.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1687538929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 843769494 + 843769495.

It is an arithmetic number, because the mean of its divisors is an integer number (843769495).

Almost surely, 2^1687538989 is an apocalyptic number.

It is an amenable number.

1687538989 is a deficient number, since it is larger than the sum of its proper divisors (1).

1687538989 is an equidigital number, since it uses as much as digits as its factorization.

1687538989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 26127360, while the sum is 64.

The square root of 1687538989 is about 41079.6663691418. Note that the first 3 decimals coincide. The cubic root of 1687538989 is about 1190.5599579692.

The spelling of 1687538989 in words is "one billion, six hundred eighty-seven million, five hundred thirty-eight thousand, nine hundred eighty-nine".