81221982 has 32 divisors (see below), whose sum is σ = 168544800. Its totient is φ = 26062848.

The previous prime is 81221963. The next prime is 81221983. The reversal of 81221982 is 28912218.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81221983) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 99994 + ... + 100802.

It is an arithmetic number, because the mean of its divisors is an integer number (5267025).

Almost surely, 2^81221982 is an apocalyptic number.

81221982 is an abundant number, since it is smaller than the sum of its proper divisors (87322818).

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

81221982 is a wasteful number, since it uses less digits than its factorization.

81221982 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1420.

The product of its digits is 4608, while the sum is 33.

The square root of 81221982 is about 9012.3238956442. The cubic root of 81221982 is about 433.0697617421.

The spelling of 81221982 in words is "eighty-one million, two hundred twenty-one thousand, nine hundred eighty-two".