81287233 has 2 divisors, whose sum is σ = 81287234. Its totient is φ = 81287232.

The previous prime is 81287207. The next prime is 81287249. The reversal of 81287233 is 33278218.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 57638464 + 23648769 = 7592^2 + 4863^2 .

It is a cyclic number.

It is not a de Polignac number, because 81287233 - 2⁵ = 81287201 is a prime.

It is a super-2 number, since 2×81287233² = 13215228497592578, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81287273) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40643616 + 40643617.

It is an arithmetic number, because the mean of its divisors is an integer number (40643617).

Almost surely, 2^81287233 is an apocalyptic number.

It is an amenable number.

81287233 is a deficient number, since it is larger than the sum of its proper divisors (1).

81287233 is an equidigital number, since it uses as much as digits as its factorization.

81287233 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16128, while the sum is 34.

The square root of 81287233 is about 9015.9432673459. The cubic root of 81287233 is about 433.1857019120.

The spelling of 81287233 in words is "eighty-one million, two hundred eighty-seven thousand, two hundred thirty-three".