21709488513 has 4 divisors (see below), whose sum is σ = 28945984688. Its totient is φ = 14472992340.

The previous prime is 21709488503. The next prime is 21709488553. The reversal of 21709488513 is 31588490712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21709488513 - 2⁹ = 21709488001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21709488503) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3618248083 + ... + 3618248088.

It is an arithmetic number, because the mean of its divisors is an integer number (7236496172).

Almost surely, 2^21709488513 is an apocalyptic number.

It is an amenable number.

21709488513 is a deficient number, since it is larger than the sum of its proper divisors (7236496175).

21709488513 is an equidigital number, since it uses as much as digits as its factorization.

21709488513 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7236496174.

The product of its (nonzero) digits is 483840, while the sum is 48.

The spelling of 21709488513 in words is "twenty-one billion, seven hundred nine million, four hundred eighty-eight thousand, five hundred thirteen".