21531200221 has 8 divisors (see below), whose sum is σ = 21995326080. Its totient is φ = 21067325088.

The previous prime is 21531200209. The next prime is 21531200261. The reversal of 21531200221 is 12200213512.

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 21531200221 - 2¹⁷ = 21531069149 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21531200261) 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, 116370 + ... + 237916.

It is an arithmetic number, because the mean of its divisors is an integer number (2749415760).

Almost surely, 2^21531200221 is an apocalyptic number.

It is an amenable number.

21531200221 is a deficient number, since it is larger than the sum of its proper divisors (464125859).

21531200221 is a wasteful number, since it uses less digits than its factorization.

21531200221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125363.

The product of its (nonzero) digits is 240, while the sum is 19.

Adding to 21531200221 its reverse (12200213512), we get a palindrome (33731413733).

The spelling of 21531200221 in words is "twenty-one billion, five hundred thirty-one million, two hundred thousand, two hundred twenty-one".