21002401 has 4 divisors (see below), whose sum is σ = 24002752. Its totient is φ = 18002052.

The previous prime is 21002393. The next prime is 21002413. The reversal of 21002401 is 10420012.

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 21002401 - 2³ = 21002393 is a prime.

It is a super-2 number, since 2×21002401² = 882201695529602, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21002431) 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, 1500165 + ... + 1500178.

It is an arithmetic number, because the mean of its divisors is an integer number (6000688).

Almost surely, 2^21002401 is an apocalyptic number.

It is an amenable number.

21002401 is a deficient number, since it is larger than the sum of its proper divisors (3000351).

21002401 is an equidigital number, since it uses as much as digits as its factorization.

21002401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3000350.

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

The square root of 21002401 is about 4582.8376580455. The cubic root of 21002401 is about 275.9029318040.

Adding to 21002401 its reverse (10420012), we get a palindrome (31422413).

The spelling of 21002401 in words is "twenty-one million, two thousand, four hundred one".