21221535344261 has 4 divisors (see below), whose sum is σ = 24253183250592. Its totient is φ = 18189887437932.

The previous prime is 21221535344209. The next prime is 21221535344297. The reversal of 21221535344261 is 16244353512212.

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 not a de Polignac number, because 21221535344261 - 2⁴² = 16823488833157 is a prime.

It is a super-2 number, since 2×21221535344261² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221535344761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1515823953155 + ... + 1515823953168.

It is an arithmetic number, because the mean of its divisors is an integer number (6063295812648).

Almost surely, 2^{21221535344261} is an apocalyptic number.

It is an amenable number.

21221535344261 is a deficient number, since it is larger than the sum of its proper divisors (3031647906331).

21221535344261 is an equidigital number, since it uses as much as digits as its factorization.

21221535344261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3031647906330.

The product of its digits is 345600, while the sum is 41.

Adding to 21221535344261 its reverse (16244353512212), we get a palindrome (37465888856473).

The spelling of 21221535344261 in words is "twenty-one trillion, two hundred twenty-one billion, five hundred thirty-five million, three hundred forty-four thousand, two hundred sixty-one".