1971991129 has 2 divisors, whose sum is σ = 1971991130. Its totient is φ = 1971991128.

The previous prime is 1971991117. The next prime is 1971991141. The reversal of 1971991129 is 9211991791.

It is a balanced prime because it is at equal distance from previous prime (1971991117) and next prime (1971991141).

It can be written as a sum of positive squares in only one way, i.e., 1532879104 + 439112025 = 39152^2 + 20955^2 .

It is an emirp because it is prime and its reverse (9211991791) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1971991129 is a prime.

It is not a weakly prime, because it can be changed into another prime (1971991159) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 985995564 + 985995565.

It is an arithmetic number, because the mean of its divisors is an integer number (985995565).

Almost surely, 2^1971991129 is an apocalyptic number.

It is an amenable number.

1971991129 is a deficient number, since it is larger than the sum of its proper divisors (1).

1971991129 is an equidigital number, since it uses as much as digits as its factorization.

1971991129 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 91854, while the sum is 49.

The square root of 1971991129 is about 44407.1067398001. The cubic root of 1971991129 is about 1254.0118842392.

The spelling of 1971991129 in words is "one billion, nine hundred seventy-one million, nine hundred ninety-one thousand, one hundred twenty-nine".