1971305681 has 2 divisors, whose sum is σ = 1971305682. Its totient is φ = 1971305680.

The previous prime is 1971305663. The next prime is 1971305701. The reversal of 1971305681 is 1865031791.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1680262081 + 291043600 = 40991^2 + 17060^2 .

It is a cyclic number.

It is not a de Polignac number, because 1971305681 - 2⁶ = 1971305617 is a prime.

It is a super-2 number, since 2×1971305681² = 7772092175885747522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1971305381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 985652840 + 985652841.

It is an arithmetic number, because the mean of its divisors is an integer number (985652841).

Almost surely, 2^1971305681 is an apocalyptic number.

It is an amenable number.

1971305681 is a deficient number, since it is larger than the sum of its proper divisors (1).

1971305681 is an equidigital number, since it uses as much as digits as its factorization.

1971305681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 45360, while the sum is 41.

The square root of 1971305681 is about 44399.3882953358. The cubic root of 1971305681 is about 1253.8665726407.

The spelling of 1971305681 in words is "one billion, nine hundred seventy-one million, three hundred five thousand, six hundred eighty-one".