81021340 has 12 divisors (see below), whose sum is σ = 170144856. Its totient is φ = 32408528.

The previous prime is 81021271. The next prime is 81021407. The reversal of 81021340 is 4312018.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2025514 + ... + 2025553.

It is an arithmetic number, because the mean of its divisors is an integer number (14178738).

Almost surely, 2^81021340 is an apocalyptic number.

It is an amenable number.

81021340 is an abundant number, since it is smaller than the sum of its proper divisors (89123516).

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

81021340 is a wasteful number, since it uses less digits than its factorization.

81021340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4051076 (or 4051074 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 81021340 is about 9001.1854774802. The cubic root of 81021340 is about 432.7128648001.

Adding to 81021340 its reverse (4312018), we get a palindrome (85333358).

The spelling of 81021340 in words is "eighty-one million, twenty-one thousand, three hundred forty".