81801628 has 6 divisors (see below), whose sum is σ = 143152856. Its totient is φ = 40900812.

The previous prime is 81801623. The next prime is 81801649. The reversal of 81801628 is 82610818.

It is a junction number, because it is equal to n+sod(n) for n = 81801593 and 81801602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81801623) 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, 10225200 + ... + 10225207.

Almost surely, 2^81801628 is an apocalyptic number.

It is an amenable number.

81801628 is a deficient number, since it is larger than the sum of its proper divisors (61351228).

81801628 is a wasteful number, since it uses less digits than its factorization.

81801628 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20450411 (or 20450409 counting only the distinct ones).

The product of its (nonzero) digits is 6144, while the sum is 34.

The square root of 81801628 is about 9044.4252443149. The cubic root of 81801628 is about 434.0975309415.

The spelling of 81801628 in words is "eighty-one million, eight hundred one thousand, six hundred twenty-eight".