1681951709 has 2 divisors, whose sum is σ = 1681951710. Its totient is φ = 1681951708.

The previous prime is 1681951673. The next prime is 1681951723. The reversal of 1681951709 is 9071591861.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1561435225 + 120516484 = 39515^2 + 10978^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1681951709 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1681951759) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 840975854 + 840975855.

It is an arithmetic number, because the mean of its divisors is an integer number (840975855).

Almost surely, 2^1681951709 is an apocalyptic number.

It is an amenable number.

1681951709 is a deficient number, since it is larger than the sum of its proper divisors (1).

1681951709 is an equidigital number, since it uses as much as digits as its factorization.

1681951709 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 136080, while the sum is 47.

The square root of 1681951709 is about 41011.6045650496. The cubic root of 1681951709 is about 1189.2445618434.

The spelling of 1681951709 in words is "one billion, six hundred eighty-one million, nine hundred fifty-one thousand, seven hundred nine".