81224641 has 2 divisors, whose sum is σ = 81224642. Its totient is φ = 81224640.

The previous prime is 81224617. The next prime is 81224653. The reversal of 81224641 is 14642218.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 70308225 + 10916416 = 8385^2 + 3304^2 .

It is a cyclic number.

It is not a de Polignac number, because 81224641 - 2⁵ = 81224609 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81224141) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40612320 + 40612321.

It is an arithmetic number, because the mean of its divisors is an integer number (40612321).

Almost surely, 2^81224641 is an apocalyptic number.

It is an amenable number.

81224641 is a deficient number, since it is larger than the sum of its proper divisors (1).

81224641 is an equidigital number, since it uses as much as digits as its factorization.

81224641 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3072, while the sum is 28.

The square root of 81224641 is about 9012.4714146565. The cubic root of 81224641 is about 433.0744875561.

Adding to 81224641 its reverse (14642218), we get a palindrome (95866859).

It can be divided in two parts, 8122464 and 1, that added together give a triangular number (8122465 = T₄₀₃₀).

The spelling of 81224641 in words is "eighty-one million, two hundred twenty-four thousand, six hundred forty-one".