8421721340 has 12 divisors (see below), whose sum is σ = 17685614856. Its totient is φ = 3368688528.

The previous prime is 8421721333. The next prime is 8421721379. The reversal of 8421721340 is 431271248.

It is a super-2 number, since 2×8421721340² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 8421721297 and 8421721306.

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, 210543014 + ... + 210543053.

It is an arithmetic number, because the mean of its divisors is an integer number (1473801238).

Almost surely, 2^8421721340 is an apocalyptic number.

It is an amenable number.

8421721340 is an abundant number, since it is smaller than the sum of its proper divisors (9263893516).

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

8421721340 is a wasteful number, since it uses less digits than its factorization.

8421721340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 421086076 (or 421086074 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 32.

The square root of 8421721340 is about 91769.9370164326. The cubic root of 8421721340 is about 2034.5433873014.

Adding to 8421721340 its reverse (431271248), we get a palindrome (8852992588).

The spelling of 8421721340 in words is "eight billion, four hundred twenty-one million, seven hundred twenty-one thousand, three hundred forty".