81964560 has 80 divisors (see below), whose sum is σ = 254965824. Its totient is φ = 21782016.

The previous prime is 81964559. The next prime is 81964567. The reversal of 81964560 is 6546918.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81964567) 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 in 15 ways as a sum of consecutive naturals, for example, 125194 + ... + 125846.

Almost surely, 2^81964560 is an apocalyptic number.

81964560 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 81964560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (127482912).

81964560 is an abundant number, since it is smaller than the sum of its proper divisors (173001264).

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

81964560 is a wasteful number, since it uses less digits than its factorization.

81964560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1192 (or 1186 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 39.

The square root of 81964560 is about 9053.4280800148. The cubic root of 81964560 is about 434.3855507677.

The spelling of 81964560 in words is "eighty-one million, nine hundred sixty-four thousand, five hundred sixty".