81642233 has 2 divisors, whose sum is σ = 81642234. Its totient is φ = 81642232.

The previous prime is 81642173. The next prime is 81642241. The reversal of 81642233 is 33224618.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 45738169 + 35904064 = 6763^2 + 5992^2 .

It is a cyclic number.

It is not a de Polignac number, because 81642233 - 2²⁶ = 14533369 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 81642196 and 81642205.

It is not a weakly prime, because it can be changed into another prime (81642283) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40821116 + 40821117.

It is an arithmetic number, because the mean of its divisors is an integer number (40821117).

Almost surely, 2^81642233 is an apocalyptic number.

It is an amenable number.

81642233 is a deficient number, since it is larger than the sum of its proper divisors (1).

81642233 is an equidigital number, since it uses as much as digits as its factorization.

81642233 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6912, while the sum is 29.

The square root of 81642233 is about 9035.6091659611. The cubic root of 81642233 is about 433.8153932528.

The spelling of 81642233 in words is "eighty-one million, six hundred forty-two thousand, two hundred thirty-three".