81772342489 has 2 divisors, whose sum is σ = 81772342490. Its totient is φ = 81772342488.

The previous prime is 81772342471. The next prime is 81772342559. The reversal of 81772342489 is 98424327718.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 76396960000 + 5375382489 = 276400^2 + 73317^2 .

It is a cyclic number.

It is not a de Polignac number, because 81772342489 - 2⁷ = 81772342361 is a prime.

It is a super-2 number, since 2×81772342489² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81772342409) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40886171244 + 40886171245.

It is an arithmetic number, because the mean of its divisors is an integer number (40886171245).

Almost surely, 2^81772342489 is an apocalyptic number.

It is an amenable number.

81772342489 is a deficient number, since it is larger than the sum of its proper divisors (1).

81772342489 is an equidigital number, since it uses as much as digits as its factorization.

81772342489 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5419008, while the sum is 55.

The spelling of 81772342489 in words is "eighty-one billion, seven hundred seventy-two million, three hundred forty-two thousand, four hundred eighty-nine".