1309999681 has 2 divisors, whose sum is σ = 1309999682. Its totient is φ = 1309999680.

The previous prime is 1309999577. The next prime is 1309999697. The reversal of 1309999681 is 1869999031.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1274490000 + 35509681 = 35700^2 + 5959^2 .

It is a cyclic number.

It is not a de Polignac number, because 1309999681 - 2⁷ = 1309999553 is a prime.

It is a super-2 number, since 2×1309999681² = 3432198328440203522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1309990681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 654999840 + 654999841.

It is an arithmetic number, because the mean of its divisors is an integer number (654999841).

Almost surely, 2^1309999681 is an apocalyptic number.

It is an amenable number.

1309999681 is a deficient number, since it is larger than the sum of its proper divisors (1).

1309999681 is an equidigital number, since it uses as much as digits as its factorization.

1309999681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 944784, while the sum is 55.

The square root of 1309999681 is about 36193.9177348902. The cubic root of 1309999681 is about 1094.1840925481.

The spelling of 1309999681 in words is "one billion, three hundred nine million, nine hundred ninety-nine thousand, six hundred eighty-one".