21718001 has 4 divisors (see below), whose sum is σ = 22305012. Its totient is φ = 21130992.

The previous prime is 21717989. The next prime is 21718033. The reversal of 21718001 is 10081712.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 19571776 + 2146225 = 4424^2 + 1465^2 .

It is a cyclic number.

It is not a de Polignac number, because 21718001 - 2⁶ = 21717937 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21718051) 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, 293450 + ... + 293523.

It is an arithmetic number, because the mean of its divisors is an integer number (5576253).

Almost surely, 2^21718001 is an apocalyptic number.

It is an amenable number.

21718001 is a deficient number, since it is larger than the sum of its proper divisors (587011).

21718001 is an equidigital number, since it uses as much as digits as its factorization.

21718001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 587010.

The product of its (nonzero) digits is 112, while the sum is 20.

The square root of 21718001 is about 4660.2576109052. The cubic root of 21718001 is about 279.0015501599.

Adding to 21718001 its reverse (10081712), we get a palindrome (31799713).

The spelling of 21718001 in words is "twenty-one million, seven hundred eighteen thousand, one".