21515655654849 has 8 divisors (see below), whose sum is σ = 28696894501600. Its totient is φ = 14339093622336.

The previous prime is 21515655654821. The next prime is 21515655654923. The reversal of 21515655654849 is 94845655651512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21515655654849 - 2⁷ = 21515655654721 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21515655654849.

It is not an unprimeable number, because it can be changed into a prime (21515655654049) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1169192824 + ... + 1169211225.

It is an arithmetic number, because the mean of its divisors is an integer number (3587111812700).

Almost surely, 2^{21515655654849} is an apocalyptic number.

It is an amenable number.

21515655654849 is a deficient number, since it is larger than the sum of its proper divisors (7181238846751).

21515655654849 is a wasteful number, since it uses less digits than its factorization.

21515655654849 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2338407119.

The product of its digits is 259200000, while the sum is 66.

The spelling of 21515655654849 in words is "twenty-one trillion, five hundred fifteen billion, six hundred fifty-five million, six hundred fifty-four thousand, eight hundred forty-nine".