21005305215340 has 12 divisors (see below), whose sum is σ = 44111140952256. Its totient is φ = 8402122086128.

The previous prime is 21005305215337. The next prime is 21005305215353. The reversal of 21005305215340 is 4351250350012.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 525132630364 + ... + 525132630403.

It is an arithmetic number, because the mean of its divisors is an integer number (3675928412688).

Almost surely, 2^{21005305215340} is an apocalyptic number.

21005305215340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21005305215340 is an abundant number, since it is smaller than the sum of its proper divisors (23105835736916).

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

21005305215340 is a wasteful number, since it uses less digits than its factorization.

21005305215340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1050265260776 (or 1050265260774 counting only the distinct ones).

The product of its (nonzero) digits is 18000, while the sum is 31.

Adding to 21005305215340 its reverse (4351250350012), we get a palindrome (25356555565352).

The spelling of 21005305215340 in words is "twenty-one trillion, five billion, three hundred five million, two hundred fifteen thousand, three hundred forty".