1987139389 has 2 divisors, whose sum is σ = 1987139390. Its totient is φ = 1987139388.

The previous prime is 1987139321. The next prime is 1987139443. The reversal of 1987139389 is 9839317891.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1487259225 + 499880164 = 38565^2 + 22358^2 .

It is a cyclic number.

It is not a de Polignac number, because 1987139389 - 2²⁷ = 1852921661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1987139489) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 993569694 + 993569695.

It is an arithmetic number, because the mean of its divisors is an integer number (993569695).

Almost surely, 2^1987139389 is an apocalyptic number.

It is an amenable number.

1987139389 is a deficient number, since it is larger than the sum of its proper divisors (1).

1987139389 is an equidigital number, since it uses as much as digits as its factorization.

1987139389 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2939328, while the sum is 58.

The square root of 1987139389 is about 44577.3416547017. The cubic root of 1987139389 is about 1257.2146815682.

It can be divided in two parts, 1987 and 139389, that added together give a square (141376 = 376²).

The spelling of 1987139389 in words is "one billion, nine hundred eighty-seven million, one hundred thirty-nine thousand, three hundred eighty-nine".