21560001 has 4 divisors (see below), whose sum is σ = 28746672. Its totient is φ = 14373332.

The previous prime is 21559999. The next prime is 21560009. The reversal of 21560001 is 10006512.

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 21560001 - 2¹ = 21559999 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21560009) 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, 3593331 + ... + 3593336.

It is an arithmetic number, because the mean of its divisors is an integer number (7186668).

Almost surely, 2^21560001 is an apocalyptic number.

It is an amenable number.

21560001 is a deficient number, since it is larger than the sum of its proper divisors (7186671).

21560001 is an equidigital number, since it uses as much as digits as its factorization.

21560001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7186670.

The product of its (nonzero) digits is 60, while the sum is 15.

The square root of 21560001 is about 4643.2748141802. The cubic root of 21560001 is about 278.3233173953.

Adding to 21560001 its reverse (10006512), we get a palindrome (31566513).

The spelling of 21560001 in words is "twenty-one million, five hundred sixty thousand, one".