1999997129 has 4 divisors (see below), whose sum is σ = 2153843076. Its totient is φ = 1846151184.

The previous prime is 1999997117. The next prime is 1999997141. The reversal of 1999997129 is 9217999991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9217999991 = 821 ⋅11227771.

It is an interprime number because it is at equal distance from previous prime (1999997117) and next prime (1999997141).

It can be written as a sum of positive squares in 2 ways, for example, as 1157836729 + 842160400 = 34027^2 + 29020^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1999997129 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1999997159) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 76922954 + ... + 76922979.

It is an arithmetic number, because the mean of its divisors is an integer number (538460769).

Almost surely, 2^1999997129 is an apocalyptic number.

It is an amenable number.

1999997129 is a deficient number, since it is larger than the sum of its proper divisors (153845947).

1999997129 is a wasteful number, since it uses less digits than its factorization.

1999997129 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153845946.

The product of its digits is 7440174, while the sum is 65.

The square root of 1999997129 is about 44721.3274512285. The cubic root of 1999997129 is about 1259.9204470224.

The spelling of 1999997129 in words is "one billion, nine hundred ninety-nine million, nine hundred ninety-seven thousand, one hundred twenty-nine".