1987090909 has 2 divisors, whose sum is σ = 1987090910. Its totient is φ = 1987090908.

The previous prime is 1987090877. The next prime is 1987090961. The reversal of 1987090909 is 9090907891.

It is an a-pointer prime, because the next prime (1987090961) can be obtained adding 1987090909 to its sum of digits (52).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1858903225 + 128187684 = 43115^2 + 11322^2 .

It is a cyclic number.

It is not a de Polignac number, because 1987090909 - 2⁵ = 1987090877 is a prime.

1987090909 is a modest number, since divided by 90909 gives 1987 as remainder.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1987090009) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 993545454 + 993545455.

It is an arithmetic number, because the mean of its divisors is an integer number (993545455).

Almost surely, 2^1987090909 is an apocalyptic number.

It is an amenable number.

1987090909 is a deficient number, since it is larger than the sum of its proper divisors (1).

1987090909 is an equidigital number, since it uses as much as digits as its factorization.

1987090909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 367416, while the sum is 52.

The square root of 1987090909 is about 44576.7978773711. The cubic root of 1987090909 is about 1257.2044574468.

The spelling of 1987090909 in words is "one billion, nine hundred eighty-seven million, ninety thousand, nine hundred nine".