21015653115281 has 4 divisors (see below), whose sum is σ = 22926167034864. Its totient is φ = 19105139195700.

The previous prime is 21015653115277. The next prime is 21015653115341. The reversal of 21015653115281 is 18251135651012.

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 21015653115281 - 2² = 21015653115277 is a prime.

It is a super-2 number, since 2×21015653115281² (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 (21015653115481) 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, 955256959775 + ... + 955256959796.

It is an arithmetic number, because the mean of its divisors is an integer number (5731541758716).

Almost surely, 2^{21015653115281} is an apocalyptic number.

It is an amenable number.

21015653115281 is a deficient number, since it is larger than the sum of its proper divisors (1910513919583).

21015653115281 is a wasteful number, since it uses less digits than its factorization.

21015653115281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1910513919582.

The product of its (nonzero) digits is 72000, while the sum is 41.

Adding to 21015653115281 its reverse (18251135651012), we get a palindrome (39266788766293).

The spelling of 21015653115281 in words is "twenty-one trillion, fifteen billion, six hundred fifty-three million, one hundred fifteen thousand, two hundred eighty-one".