1681591 has 2 divisors, whose sum is σ = 1681592. Its totient is φ = 1681590.

The previous prime is 1681579. The next prime is 1681597. The reversal of 1681591 is 1951861.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1681591 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1681597) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 840795 + 840796.

It is an arithmetic number, because the mean of its divisors is an integer number (840796).

2^1681591 is an apocalyptic number.

1681591 is a deficient number, since it is larger than the sum of its proper divisors (1).

1681591 is an equidigital number, since it uses as much as digits as its factorization.

1681591 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2160, while the sum is 31.

The square root of 1681591 is about 1296.7617360178. The cubic root of 1681591 is about 118.9159541193.

The spelling of 1681591 in words is "one million, six hundred eighty-one thousand, five hundred ninety-one".