81261936 has 120 divisors (see below), whose sum is σ = 273653120. Its totient is φ = 21990528.

The previous prime is 81261913. The next prime is 81261977. The reversal of 81261936 is 63916218.

81261936 is a `hidden beast` number, since 8 + 1 + 2 + 619 + 36 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 81261936.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 17031 + ... + 21273.

Almost surely, 2^81261936 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 81261936, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (136826560).

81261936 is an abundant number, since it is smaller than the sum of its proper divisors (192391184).

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

81261936 is a wasteful number, since it uses less digits than its factorization.

81261936 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4283 (or 4274 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 81261936 is about 9014.5402544999. The cubic root of 81261936 is about 433.1407607191.

The spelling of 81261936 in words is "eighty-one million, two hundred sixty-one thousand, nine hundred thirty-six".