21025004220561 has 8 divisors (see below), whose sum is σ = 30581824320864. Its totient is φ = 12742426800320.

The previous prime is 21025004220541. The next prime is 21025004220593. The reversal of 21025004220561 is 16502240052012.

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 21025004220561 - 2¹⁰ = 21025004219537 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21025004220541) 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, 318560669976 + ... + 318560670041.

It is an arithmetic number, because the mean of its divisors is an integer number (3822728040108).

Almost surely, 2^{21025004220561} is an apocalyptic number.

It is an amenable number.

21025004220561 is a deficient number, since it is larger than the sum of its proper divisors (9556820100303).

21025004220561 is a wasteful number, since it uses less digits than its factorization.

21025004220561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 637121340031.

The product of its (nonzero) digits is 9600, while the sum is 30.

Adding to 21025004220561 its reverse (16502240052012), we get a palindrome (37527244272573).

The spelling of 21025004220561 in words is "twenty-one trillion, twenty-five billion, four million, two hundred twenty thousand, five hundred sixty-one".