21427001 has 4 divisors (see below), whose sum is σ = 21436404. Its totient is φ = 21417600.

The previous prime is 21426997. The next prime is 21427013. The reversal of 21427001 is 10072412.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 9703225 + 11723776 = 3115^2 + 3424^2 .

It is a cyclic number.

It is not a de Polignac number, because 21427001 - 2² = 21426997 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21427501) 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, 1121 + ... + 6641.

It is an arithmetic number, because the mean of its divisors is an integer number (5359101).

Almost surely, 2^21427001 is an apocalyptic number.

It is an amenable number.

21427001 is a deficient number, since it is larger than the sum of its proper divisors (9403).

21427001 is an equidigital number, since it uses as much as digits as its factorization.

21427001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9402.

The product of its (nonzero) digits is 112, while the sum is 17.

The square root of 21427001 is about 4628.9308700822. The cubic root of 21427001 is about 277.7498266927.

Adding to 21427001 its reverse (10072412), we get a palindrome (31499413).

The spelling of 21427001 in words is "twenty-one million, four hundred twenty-seven thousand, one".