81809468 has 24 divisors (see below), whose sum is σ = 154429968. Its totient is φ = 37696896.

The previous prime is 81809467. The next prime is 81809471. The reversal of 81809468 is 86490818.

It is a happy number.

81809468 is nontrivially palindromic in base 8.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81809467) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 52955 + ... + 54477.

It is an arithmetic number, because the mean of its divisors is an integer number (6434582).

Almost surely, 2^81809468 is an apocalyptic number.

It is an amenable number.

81809468 is a deficient number, since it is larger than the sum of its proper divisors (72620500).

81809468 is a wasteful number, since it uses less digits than its factorization.

81809468 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2573 (or 2571 counting only the distinct ones).

The product of its (nonzero) digits is 110592, while the sum is 44.

The square root of 81809468 is about 9044.8586500840. The cubic root of 81809468 is about 434.1113987011. Note that the first 3 decimals are identical.

The spelling of 81809468 in words is "eighty-one million, eight hundred nine thousand, four hundred sixty-eight".