81989801 has 2 divisors, whose sum is σ = 81989802. Its totient is φ = 81989800.

The previous prime is 81989771. The next prime is 81989821. The reversal of 81989801 is 10898918.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 57229225 + 24760576 = 7565^2 + 4976^2 .

It is a cyclic number.

It is not a de Polignac number, because 81989801 - 2¹⁴ = 81973417 is a prime.

It is not a weakly prime, because it can be changed into another prime (81989821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40994900 + 40994901.

It is an arithmetic number, because the mean of its divisors is an integer number (40994901).

Almost surely, 2^81989801 is an apocalyptic number.

It is an amenable number.

81989801 is a deficient number, since it is larger than the sum of its proper divisors (1).

81989801 is an equidigital number, since it uses as much as digits as its factorization.

81989801 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 41472, while the sum is 44.

The square root of 81989801 is about 9054.8219750584. The cubic root of 81989801 is about 434.4301358924.

The spelling of 81989801 in words is "eighty-one million, nine hundred eighty-nine thousand, eight hundred one".