13500615721 has 4 divisors (see below), whose sum is σ = 13787862912. Its totient is φ = 13213368532.

The previous prime is 13500615703. The next prime is 13500615749. The reversal of 13500615721 is 12751600531.

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 a cyclic number.

It is not a de Polignac number, because 13500615721 - 2¹¹ = 13500613673 is a prime.

It is a super-2 number, since 2×13500615721² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13500615521) 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, 143623525 + ... + 143623618.

It is an arithmetic number, because the mean of its divisors is an integer number (3446965728).

Almost surely, 2^13500615721 is an apocalyptic number.

It is an amenable number.

13500615721 is a deficient number, since it is larger than the sum of its proper divisors (287247191).

13500615721 is an equidigital number, since it uses as much as digits as its factorization.

13500615721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 287247190.

The product of its (nonzero) digits is 6300, while the sum is 31.

The spelling of 13500615721 in words is "thirteen billion, five hundred million, six hundred fifteen thousand, seven hundred twenty-one".