21720355038519 has 4 divisors (see below), whose sum is σ = 28960473384696. Its totient is φ = 14480236692344.

The previous prime is 21720355038509. The next prime is 21720355038523. The reversal of 21720355038519 is 91583055302712.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21720355038519 - 2¹² = 21720355034423 is a prime.

It is a super-2 number, since 2×21720355038519² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21720355038509) 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, 3620059173084 + ... + 3620059173089.

It is an arithmetic number, because the mean of its divisors is an integer number (7240118346174).

Almost surely, 2^{21720355038519} is an apocalyptic number.

21720355038519 is a deficient number, since it is larger than the sum of its proper divisors (7240118346177).

21720355038519 is an equidigital number, since it uses as much as digits as its factorization.

21720355038519 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7240118346176.

The product of its (nonzero) digits is 2268000, while the sum is 51.

The spelling of 21720355038519 in words is "twenty-one trillion, seven hundred twenty billion, three hundred fifty-five million, thirty-eight thousand, five hundred nineteen".