21465221221 has 8 divisors (see below), whose sum is σ = 22698079488. Its totient is φ = 20266140000.

The previous prime is 21465221161. The next prime is 21465221249. The reversal of 21465221221 is 12212256412.

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 21465221221 - 2²⁷ = 21331003493 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 21465221221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21465221251) 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, 8442955 + ... + 8445496.

It is an arithmetic number, because the mean of its divisors is an integer number (2837259936).

Almost surely, 2^21465221221 is an apocalyptic number.

It is an amenable number.

21465221221 is a deficient number, since it is larger than the sum of its proper divisors (1232858267).

21465221221 is a wasteful number, since it uses less digits than its factorization.

21465221221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16888523.

The product of its digits is 3840, while the sum is 28.

Adding to 21465221221 its reverse (12212256412), we get a palindrome (33677477633).

The spelling of 21465221221 in words is "twenty-one billion, four hundred sixty-five million, two hundred twenty-one thousand, two hundred twenty-one".