81881370 has 96 divisors (see below), whose sum is σ = 222513408. Its totient is φ = 20870784.

The previous prime is 81881369. The next prime is 81881377. The reversal of 81881370 is 7318818.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81881377) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 222927 + ... + 223293.

It is an arithmetic number, because the mean of its divisors is an integer number (2317848).

Almost surely, 2^81881370 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81881370, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (111256704).

81881370 is an abundant number, since it is smaller than the sum of its proper divisors (140632038).

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

81881370 is a wasteful number, since it uses less digits than its factorization.

81881370 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 484 (or 481 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 36.

The square root of 81881370 is about 9048.8325213809. The cubic root of 81881370 is about 434.2385410256.

The spelling of 81881370 in words is "eighty-one million, eight hundred eighty-one thousand, three hundred seventy".