81530233 has 2 divisors, whose sum is σ = 81530234. Its totient is φ = 81530232.

The previous prime is 81530231. The next prime is 81530243. The reversal of 81530233 is 33203518.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 78801129 + 2729104 = 8877^2 + 1652^2 .

It is a cyclic number.

It is not a de Polignac number, because 81530233 - 2¹ = 81530231 is a prime.

Together with 81530231, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 81530198 and 81530207.

It is not a weakly prime, because it can be changed into another prime (81530231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40765116 + 40765117.

It is an arithmetic number, because the mean of its divisors is an integer number (40765117).

Almost surely, 2^81530233 is an apocalyptic number.

It is an amenable number.

81530233 is a deficient number, since it is larger than the sum of its proper divisors (1).

81530233 is an equidigital number, since it uses as much as digits as its factorization.

81530233 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2160, while the sum is 25.

The square root of 81530233 is about 9029.4093383787. The cubic root of 81530233 is about 433.6169275111.

The spelling of 81530233 in words is "eighty-one million, five hundred thirty thousand, two hundred thirty-three".