81962191 has 2 divisors, whose sum is σ = 81962192. Its totient is φ = 81962190.

The previous prime is 81962189. The next prime is 81962197. The reversal of 81962191 is 19126918.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81962191 - 2¹ = 81962189 is a prime.

Together with 81962189, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81962191.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81962197) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40981095 + 40981096.

It is an arithmetic number, because the mean of its divisors is an integer number (40981096).

Almost surely, 2^81962191 is an apocalyptic number.

81962191 is a deficient number, since it is larger than the sum of its proper divisors (1).

81962191 is an equidigital number, since it uses as much as digits as its factorization.

81962191 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7776, while the sum is 37.

The square root of 81962191 is about 9053.2972446507. The cubic root of 81962191 is about 434.3813657504.

The spelling of 81962191 in words is "eighty-one million, nine hundred sixty-two thousand, one hundred ninety-one".