81887820 has 192 divisors, whose sum is σ = 280627200. Its totient is φ = 17799936.

The previous prime is 81887807. The next prime is 81887821. The reversal of 81887820 is 2878818.

It is a happy number.

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

It is not an unprimeable number, because it can be changed into a prime (81887821) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 473254 + ... + 473426.

It is an arithmetic number, because the mean of its divisors is an integer number (1461600).

Almost surely, 2^81887820 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 81887820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (140313600).

81887820 is an abundant number, since it is smaller than the sum of its proper divisors (198739380).

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

81887820 is a wasteful number, since it uses less digits than its factorization.

81887820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 229 (or 213 counting only the distinct ones).

The product of its (nonzero) digits is 57344, while the sum is 42.

The square root of 81887820 is about 9049.1889139304. The cubic root of 81887820 is about 434.2499427443.

The spelling of 81887820 in words is "eighty-one million, eight hundred eighty-seven thousand, eight hundred twenty".