1685716381 has 2 divisors, whose sum is σ = 1685716382. Its totient is φ = 1685716380.

The previous prime is 1685716367. The next prime is 1685716387. The reversal of 1685716381 is 1836175861.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 944025625 + 741690756 = 30725^2 + 27234^2 .

It is a cyclic number.

It is not a de Polignac number, because 1685716381 - 2²¹ = 1683619229 is a prime.

It is a super-2 number, since 2×1685716381² = 5683279434343474322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1685716387) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 842858190 + 842858191.

It is an arithmetic number, because the mean of its divisors is an integer number (842858191).

Almost surely, 2^1685716381 is an apocalyptic number.

It is an amenable number.

1685716381 is a deficient number, since it is larger than the sum of its proper divisors (1).

1685716381 is an equidigital number, since it uses as much as digits as its factorization.

1685716381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 241920, while the sum is 46.

The square root of 1685716381 is about 41057.4765542160. The cubic root of 1685716381 is about 1190.1311864883.

The spelling of 1685716381 in words is "one billion, six hundred eighty-five million, seven hundred sixteen thousand, three hundred eighty-one".