21555534035221 has 4 divisors (see below), whose sum is σ = 21557236831200. Its totient is φ = 21553831239244.

The previous prime is 21555534035207. The next prime is 21555534035311. The reversal of 21555534035221 is 12253043555512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21555534035221 - 2²⁷ = 21555399817493 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 (21555534035621) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 851379001 + ... + 851404318.

It is an arithmetic number, because the mean of its divisors is an integer number (5389309207800).

Almost surely, 2^{21555534035221} is an apocalyptic number.

It is an amenable number.

21555534035221 is a deficient number, since it is larger than the sum of its proper divisors (1702795979).

21555534035221 is a wasteful number, since it uses less digits than its factorization.

21555534035221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1702795978.

The product of its (nonzero) digits is 900000, while the sum is 43.

The spelling of 21555534035221 in words is "twenty-one trillion, five hundred fifty-five billion, five hundred thirty-four million, thirty-five thousand, two hundred twenty-one".