1681980581 has 2 divisors, whose sum is σ = 1681980582. Its totient is φ = 1681980580.

The previous prime is 1681980577. The next prime is 1681980583. The reversal of 1681980581 is 1850891861.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1321322500 + 360658081 = 36350^2 + 18991^2 .

It is a cyclic number.

It is not a de Polignac number, because 1681980581 - 2² = 1681980577 is a prime.

It is a super-2 number, since 2×1681980581² = 5658117349722195122, which contains 22 as substring.

Together with 1681980583, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1681980583) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 840990290 + 840990291.

It is an arithmetic number, because the mean of its divisors is an integer number (840990291).

Almost surely, 2^1681980581 is an apocalyptic number.

It is an amenable number.

1681980581 is a deficient number, since it is larger than the sum of its proper divisors (1).

1681980581 is an equidigital number, since it uses as much as digits as its factorization.

1681980581 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 138240, while the sum is 47.

The square root of 1681980581 is about 41011.9565614712. The cubic root of 1681980581 is about 1189.2513665715.

The spelling of 1681980581 in words is "one billion, six hundred eighty-one million, nine hundred eighty thousand, five hundred eighty-one".