21155013320521 has 8 divisors (see below), whose sum is σ = 21942239284800. Its totient is φ = 20371636872720.

The previous prime is 21155013320513. The next prime is 21155013320629. The reversal of 21155013320521 is 12502331055112.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21155013320521 - 2³ = 21155013320513 is a prime.

It is a super-2 number, since 2×21155013320521² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21155013320921) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 962367925 + ... + 962389906.

It is an arithmetic number, because the mean of its divisors is an integer number (2742779910600).

Almost surely, 2^{21155013320521} is an apocalyptic number.

It is an amenable number.

21155013320521 is a deficient number, since it is larger than the sum of its proper divisors (787225964279).

21155013320521 is a wasteful number, since it uses less digits than its factorization.

21155013320521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1924758239.

The product of its (nonzero) digits is 9000, while the sum is 31.

Adding to 21155013320521 its reverse (12502331055112), we get a palindrome (33657344375633).

The spelling of 21155013320521 in words is "twenty-one trillion, one hundred fifty-five billion, thirteen million, three hundred twenty thousand, five hundred twenty-one".