81964554 has 48 divisors (see below), whose sum is σ = 193161600. Its totient is φ = 23115456.

The previous prime is 81964543. The next prime is 81964559. The reversal of 81964554 is 45546918.

It is a super-3 number, since 3×81964554³ (a number of 25 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81964559) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 21462 + ... + 24990.

It is an arithmetic number, because the mean of its divisors is an integer number (4024200).

Almost surely, 2^81964554 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81964554, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (96580800).

81964554 is an abundant number, since it is smaller than the sum of its proper divisors (111197046).

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

81964554 is a wasteful number, since it uses less digits than its factorization.

81964554 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3627 (or 3620 counting only the distinct ones).

The product of its digits is 172800, while the sum is 42.

The square root of 81964554 is about 9053.4277486486. The cubic root of 81964554 is about 434.3855401683.

The spelling of 81964554 in words is "eighty-one million, nine hundred sixty-four thousand, five hundred fifty-four".