81963520 has 80 divisors (see below), whose sum is σ = 199092168. Its totient is φ = 32358400.

The previous prime is 81963517. The next prime is 81963521. The reversal of 81963520 is 2536918.

It can be written as a sum of positive squares in 4 ways, for example, as 66846976 + 15116544 = 8176^2 + 3888^2 .

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×81963520² = 13436037221580800, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81963521) 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, 258402 + ... + 258718.

Almost surely, 2^81963520 is an apocalyptic number.

81963520 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81963520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (99546084).

81963520 is an abundant number, since it is smaller than the sum of its proper divisors (117128648).

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

81963520 is a wasteful number, since it uses less digits than its factorization.

81963520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 441 (or 425 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 34.

The square root of 81963520 is about 9053.3706430257. The cubic root of 81963520 is about 434.3837135391.

The spelling of 81963520 in words is "eighty-one million, nine hundred sixty-three thousand, five hundred twenty".