81654569 has 2 divisors, whose sum is σ = 81654570. Its totient is φ = 81654568.

The previous prime is 81654541. The next prime is 81654581. The reversal of 81654569 is 96545618.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 61042969 + 20611600 = 7813^2 + 4540^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81654569 is a prime.

It is a super-2 number, since 2×81654569² = 13334937277151522, which contains 22 as substring.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is not a weakly prime, because it can be changed into another prime (81654509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40827284 + 40827285.

It is an arithmetic number, because the mean of its divisors is an integer number (40827285).

Almost surely, 2^81654569 is an apocalyptic number.

It is an amenable number.

81654569 is a deficient number, since it is larger than the sum of its proper divisors (1).

81654569 is an equidigital number, since it uses as much as digits as its factorization.

81654569 is an evil number, because the sum of its binary digits is even.

The product of its digits is 259200, while the sum is 44.

The square root of 81654569 is about 9036.2917726244. The cubic root of 81654569 is about 433.8372417373.

The spelling of 81654569 in words is "eighty-one million, six hundred fifty-four thousand, five hundred sixty-nine".