81218970 has 128 divisors (see below), whose sum is σ = 252864000. Its totient is φ = 18543168.

The previous prime is 81218953. The next prime is 81218983. The reversal of 81218970 is 7981218.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 92172 + ... + 93048.

It is an arithmetic number, because the mean of its divisors is an integer number (1975500).

Almost surely, 2^81218970 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81218970, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (126432000).

81218970 is an abundant number, since it is smaller than the sum of its proper divisors (171645030).

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

81218970 is a wasteful number, since it uses less digits than its factorization.

81218970 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 914 (or 894 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 36.

The square root of 81218970 is about 9012.1567895815. The cubic root of 81218970 is about 433.0644084202.

The spelling of 81218970 in words is "eighty-one million, two hundred eighteen thousand, nine hundred seventy".