81884920 has 128 divisors (see below), whose sum is σ = 215006400. Its totient is φ = 27795456.

The previous prime is 81884917. The next prime is 81884923. The reversal of 81884920 is 2948818.

It is an interprime number because it is at equal distance from previous prime (81884917) and next prime (81884923).

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81884923) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 521482 + ... + 521638.

Almost surely, 2^81884920 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 81884920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (107503200).

81884920 is an abundant number, since it is smaller than the sum of its proper divisors (133121480).

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

81884920 is a wasteful number, since it uses less digits than its factorization.

81884920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 257 (or 253 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 40.

The square root of 81884920 is about 9049.0286771565. The cubic root of 81884920 is about 434.2448164643.

The spelling of 81884920 in words is "eighty-one million, eight hundred eighty-four thousand, nine hundred twenty".