21501221573 has 8 divisors (see below), whose sum is σ = 23173115616. Its totient is φ = 19831892400.

The previous prime is 21501221569. The next prime is 21501221603. The reversal of 21501221573 is 37512210512.

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 21501221573 - 2² = 21501221569 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 (21501221473) 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, 623783 + ... + 657348.

It is an arithmetic number, because the mean of its divisors is an integer number (2896639452).

Almost surely, 2^21501221573 is an apocalyptic number.

It is an amenable number.

21501221573 is a deficient number, since it is larger than the sum of its proper divisors (1671894043).

21501221573 is a wasteful number, since it uses less digits than its factorization.

21501221573 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1282435.

The product of its (nonzero) digits is 4200, while the sum is 29.

The spelling of 21501221573 in words is "twenty-one billion, five hundred one million, two hundred twenty-one thousand, five hundred seventy-three".