81662731 has 2 divisors, whose sum is σ = 81662732. Its totient is φ = 81662730.

The previous prime is 81662729. The next prime is 81662767. The reversal of 81662731 is 13726618.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81662731 - 2¹ = 81662729 is a prime.

It is a super-2 number, since 2×81662731² = 13337603268756722, which contains 22 as substring.

Together with 81662729, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (81662131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40831365 + 40831366.

It is an arithmetic number, because the mean of its divisors is an integer number (40831366).

Almost surely, 2^81662731 is an apocalyptic number.

81662731 is a deficient number, since it is larger than the sum of its proper divisors (1).

81662731 is an equidigital number, since it uses as much as digits as its factorization.

81662731 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12096, while the sum is 34.

The square root of 81662731 is about 9036.7433846491. The cubic root of 81662731 is about 433.8516963748.

The spelling of 81662731 in words is "eighty-one million, six hundred sixty-two thousand, seven hundred thirty-one".