21504003042221 has 16 divisors (see below), whose sum is σ = 25847433980928. Its totient is φ = 17500866739200.

The previous prime is 21504003042209. The next prime is 21504003042271. The reversal of 21504003042221 is 12224030040512.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21504003042221 is a prime.

It is a super-2 number, since 2×21504003042221² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21504003042271) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 934863860 + ... + 934886861.

It is an arithmetic number, because the mean of its divisors is an integer number (1615464623808).

Almost surely, 2^{21504003042221} is an apocalyptic number.

It is an amenable number.

21504003042221 is a deficient number, since it is larger than the sum of its proper divisors (4343430938707).

21504003042221 is a wasteful number, since it uses less digits than its factorization.

21504003042221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1869750812.

The product of its (nonzero) digits is 3840, while the sum is 26.

Adding to 21504003042221 its reverse (12224030040512), we get a palindrome (33728033082733).

The spelling of 21504003042221 in words is "twenty-one trillion, five hundred four billion, three million, forty-two thousand, two hundred twenty-one".