21721105325513 has 16 divisors (see below), whose sum is σ = 23966952157440. Its totient is φ = 19684167334480.

The previous prime is 21721105325461. The next prime is 21721105325531. The reversal of 21721105325513 is 31552350112712.

It is not a de Polignac number, because 21721105325513 - 2⁶ = 21721105325449 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21721105325113) 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, 25318433 + ... + 26162286.

It is an arithmetic number, because the mean of its divisors is an integer number (1497934509840).

Almost surely, 2^{21721105325513} is an apocalyptic number.

It is an amenable number.

21721105325513 is a deficient number, since it is larger than the sum of its proper divisors (2245846831927).

21721105325513 is an equidigital number, since it uses as much as digits as its factorization.

21721105325513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51481069 (or 51481047 counting only the distinct ones).

The product of its (nonzero) digits is 63000, while the sum is 38.

The spelling of 21721105325513 in words is "twenty-one trillion, seven hundred twenty-one billion, one hundred five million, three hundred twenty-five thousand, five hundred thirteen".