81019936 has 48 divisors (see below), whose sum is σ = 167915160. Its totient is φ = 38430720.

The previous prime is 81019931. The next prime is 81019937. The reversal of 81019936 is 63991018.

It can be written as a sum of positive squares in 4 ways, for example, as 66912400 + 14107536 = 8180^2 + 3756^2 .

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a junction number, because it is equal to n+sod(n) for n = 81019895 and 81019904.

It is not an unprimeable number, because it can be changed into a prime (81019931) 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, 47710 + ... + 49378.

Almost surely, 2^81019936 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81019936, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (83957580).

81019936 is an abundant number, since it is smaller than the sum of its proper divisors (86895224).

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

81019936 is a wasteful number, since it uses less digits than its factorization.

81019936 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1757 (or 1749 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 37.

The square root of 81019936 is about 9001.1074874151. The cubic root of 81019936 is about 432.7103653254.

The spelling of 81019936 in words is "eighty-one million, nineteen thousand, nine hundred thirty-six".