81661733 has 2 divisors, whose sum is σ = 81661734. Its totient is φ = 81661732.

The previous prime is 81661721. The next prime is 81661739. The reversal of 81661733 is 33716618.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66552964 + 15108769 = 8158^2 + 3887^2 .

It is a cyclic number.

It is not a de Polignac number, because 81661733 - 2¹² = 81657637 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 81661693 and 81661702.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81661739) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40830866 + 40830867.

It is an arithmetic number, because the mean of its divisors is an integer number (40830867).

Almost surely, 2^81661733 is an apocalyptic number.

It is an amenable number.

81661733 is a deficient number, since it is larger than the sum of its proper divisors (1).

81661733 is an equidigital number, since it uses as much as digits as its factorization.

81661733 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18144, while the sum is 35.

The square root of 81661733 is about 9036.6881654730. The cubic root of 81661733 is about 433.8499290008.

The spelling of 81661733 in words is "eighty-one million, six hundred sixty-one thousand, seven hundred thirty-three".