81768551 has 2 divisors, whose sum is σ = 81768552. Its totient is φ = 81768550.

The previous prime is 81768517. The next prime is 81768563. The reversal of 81768551 is 15586718.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81768551 - 2¹⁰ = 81767527 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 81768499 and 81768508.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81768581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40884275 + 40884276.

It is an arithmetic number, because the mean of its divisors is an integer number (40884276).

Almost surely, 2^81768551 is an apocalyptic number.

81768551 is a deficient number, since it is larger than the sum of its proper divisors (1).

81768551 is an equidigital number, since it uses as much as digits as its factorization.

81768551 is an evil number, because the sum of its binary digits is even.

The product of its digits is 67200, while the sum is 41.

The square root of 81768551 is about 9042.5964744646. The cubic root of 81768551 is about 434.0390130361.

The spelling of 81768551 in words is "eighty-one million, seven hundred sixty-eight thousand, five hundred fifty-one".