21560421 has 8 divisors (see below), whose sum is σ = 30260320. Its totient is φ = 13617072.

The previous prime is 21560411. The next prime is 21560423. The reversal of 21560421 is 12406512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21560421 - 2¹⁴ = 21544037 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21560423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 189070 + ... + 189183.

It is an arithmetic number, because the mean of its divisors is an integer number (3782540).

Almost surely, 2^21560421 is an apocalyptic number.

It is an amenable number.

21560421 is a deficient number, since it is larger than the sum of its proper divisors (8699899).

21560421 is a wasteful number, since it uses less digits than its factorization.

21560421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 378275.

The product of its (nonzero) digits is 480, while the sum is 21.

The square root of 21560421 is about 4643.3200406606. The cubic root of 21560421 is about 278.3251246777.

Adding to 21560421 its reverse (12406512), we get a palindrome (33966933).

The spelling of 21560421 in words is "twenty-one million, five hundred sixty thousand, four hundred twenty-one".