81900443 has 2 divisors, whose sum is σ = 81900444. Its totient is φ = 81900442.

The previous prime is 81900439. The next prime is 81900451. The reversal of 81900443 is 34400918.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81900443 - 2² = 81900439 is a prime.

It is not a weakly prime, because it can be changed into another prime (81900473) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40950221 + 40950222.

It is an arithmetic number, because the mean of its divisors is an integer number (40950222).

Almost surely, 2^81900443 is an apocalyptic number.

81900443 is a deficient number, since it is larger than the sum of its proper divisors (1).

81900443 is an equidigital number, since it uses as much as digits as its factorization.

81900443 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3456, while the sum is 29.

The square root of 81900443 is about 9049.8863528776. The cubic root of 81900443 is about 434.2722547943.

The spelling of 81900443 in words is "eighty-one million, nine hundred thousand, four hundred forty-three".