19987129 has 2 divisors, whose sum is σ = 19987130. Its totient is φ = 19987128.

The previous prime is 19987127. The next prime is 19987151. The reversal of 19987129 is 92178991.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19713600 + 273529 = 4440^2 + 523^2 .

It is a cyclic number.

It is not a de Polignac number, because 19987129 - 2¹ = 19987127 is a prime.

Together with 19987127, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (19987127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9993564 + 9993565.

It is an arithmetic number, because the mean of its divisors is an integer number (9993565).

Almost surely, 2^19987129 is an apocalyptic number.

It is an amenable number.

19987129 is a deficient number, since it is larger than the sum of its proper divisors (1).

19987129 is an equidigital number, since it uses as much as digits as its factorization.

19987129 is an evil number, because the sum of its binary digits is even.

The product of its digits is 81648, while the sum is 46.

The square root of 19987129 is about 4470.6967018576. The cubic root of 19987129 is about 271.3835203821.

The spelling of 19987129 in words is "nineteen million, nine hundred eighty-seven thousand, one hundred twenty-nine".