21004214221 has 16 divisors (see below), whose sum is σ = 24217531200. Its totient is φ = 18082407168.

The previous prime is 21004214219. The next prime is 21004214233. The reversal of 21004214221 is 12241240012.

It is a cyclic number.

It is not a de Polignac number, because 21004214221 - 2¹ = 21004214219 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21004214201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1111815 + ... + 1130548.

It is an arithmetic number, because the mean of its divisors is an integer number (1513595700).

Almost surely, 2^21004214221 is an apocalyptic number.

It is an amenable number.

21004214221 is a deficient number, since it is larger than the sum of its proper divisors (3213316979).

21004214221 is a wasteful number, since it uses less digits than its factorization.

21004214221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2242428.

The product of its (nonzero) digits is 256, while the sum is 19.

Adding to 21004214221 its reverse (12241240012), we get a palindrome (33245454233).

It can be divided in two parts, 21004 and 214221, that added together give a square (235225 = 485²).

The spelling of 21004214221 in words is "twenty-one billion, four million, two hundred fourteen thousand, two hundred twenty-one".