1291639901 has 2 divisors, whose sum is σ = 1291639902. Its totient is φ = 1291639900.

The previous prime is 1291639883. The next prime is 1291639939. The reversal of 1291639901 is 1099361921.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1258404676 + 33235225 = 35474^2 + 5765^2 .

It is a cyclic number.

It is not a de Polignac number, because 1291639901 - 2⁶ = 1291639837 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1291639981) 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, 645819950 + 645819951.

It is an arithmetic number, because the mean of its divisors is an integer number (645819951).

Almost surely, 2^1291639901 is an apocalyptic number.

It is an amenable number.

1291639901 is a deficient number, since it is larger than the sum of its proper divisors (1).

1291639901 is an equidigital number, since it uses as much as digits as its factorization.

1291639901 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 26244, while the sum is 41.

The square root of 1291639901 is about 35939.3920510629. The cubic root of 1291639901 is about 1089.0483237278.

The spelling of 1291639901 in words is "one billion, two hundred ninety-one million, six hundred thirty-nine thousand, nine hundred one".