81942251 has 2 divisors, whose sum is σ = 81942252. Its totient is φ = 81942250.

The previous prime is 81942239. The next prime is 81942253. The reversal of 81942251 is 15224918.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81942251 - 2¹⁰ = 81941227 is a prime.

Together with 81942253, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81942253) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40971125 + 40971126.

It is an arithmetic number, because the mean of its divisors is an integer number (40971126).

Almost surely, 2^81942251 is an apocalyptic number.

81942251 is a deficient number, since it is larger than the sum of its proper divisors (1).

81942251 is an equidigital number, since it uses as much as digits as its factorization.

81942251 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5760, while the sum is 32.

The square root of 81942251 is about 9052.1959214325. The cubic root of 81942251 is about 434.3461370398.

The spelling of 81942251 in words is "eighty-one million, nine hundred forty-two thousand, two hundred fifty-one".