21154424221 has 8 divisors (see below), whose sum is σ = 24187731264. Its totient is φ = 18123928800.

The previous prime is 21154424219. The next prime is 21154424237. The reversal of 21154424221 is 12242445112.

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 21154424221 - 2¹ = 21154424219 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 21154424221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21154424201) 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, 686755 + ... + 716896.

It is an arithmetic number, because the mean of its divisors is an integer number (3023466408).

Almost surely, 2^21154424221 is an apocalyptic number.

It is an amenable number.

21154424221 is a deficient number, since it is larger than the sum of its proper divisors (3033307043).

21154424221 is a wasteful number, since it uses less digits than its factorization.

21154424221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1405811.

The product of its digits is 5120, while the sum is 28.

Adding to 21154424221 its reverse (12242445112), we get a palindrome (33396869333).

The spelling of 21154424221 in words is "twenty-one billion, one hundred fifty-four million, four hundred twenty-four thousand, two hundred twenty-one".