21042001 has 8 divisors (see below), whose sum is σ = 21295808. Its totient is φ = 20790000.

The previous prime is 21041989. The next prime is 21042013. The reversal of 21042001 is 10024012.

It is an interprime number because it is at equal distance from previous prime (21041989) and next prime (21042013).

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 21042001 - 2¹³ = 21033809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21042601) 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, 49771 + ... + 50191.

It is an arithmetic number, because the mean of its divisors is an integer number (2661976).

It is a Poulet number, since it divides 2^21042000-1.

Almost surely, 2^21042001 is an apocalyptic number.

It is an amenable number.

21042001 is a deficient number, since it is larger than the sum of its proper divisors (253807).

21042001 is a wasteful number, since it uses less digits than its factorization.

21042001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 903.

The product of its (nonzero) digits is 16, while the sum is 10.

The square root of 21042001 is about 4587.1560906514. The cubic root of 21042001 is about 276.0762278072.

Adding to 21042001 its reverse (10024012), we get a palindrome (31066013).

The spelling of 21042001 in words is "twenty-one million, forty-two thousand, one".