81633520 has 20 divisors (see below), whose sum is σ = 189798120. Its totient is φ = 32653376.

The previous prime is 81633499. The next prime is 81633529. The reversal of 81633520 is 2533618.

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81633529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 510130 + ... + 510289.

It is an arithmetic number, because the mean of its divisors is an integer number (9489906).

Almost surely, 2^81633520 is an apocalyptic number.

81633520 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81633520 is an abundant number, since it is smaller than the sum of its proper divisors (108164600).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81633520 is a wasteful number, since it uses less digits than its factorization.

81633520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1020432 (or 1020426 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 81633520 is about 9035.1270051948. The cubic root of 81633520 is about 433.7999601947.

It can be divided in two parts, 8 and 1633520, that added together give a triangular number (1633528 = T₁₈₀₇).

The spelling of 81633520 in words is "eighty-one million, six hundred thirty-three thousand, five hundred twenty".