21002441 has 4 divisors (see below), whose sum is σ = 21062292. Its totient is φ = 20942592.

The previous prime is 21002431. The next prime is 21002461. The reversal of 21002441 is 14420012.

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 10374841 + 10627600 = 3221^2 + 3260^2 .

It is a cyclic number.

It is not a de Polignac number, because 21002441 - 2¹⁰ = 21001417 is a prime.

It is a super-2 number, since 2×21002441² = 882205055916962, 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, 29396 + ... + 30101.

It is an arithmetic number, because the mean of its divisors is an integer number (5265573).

Almost surely, 2^21002441 is an apocalyptic number.

It is an amenable number.

21002441 is a deficient number, since it is larger than the sum of its proper divisors (59851).

21002441 is an equidigital number, since it uses as much as digits as its factorization.

21002441 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59850.

The product of its (nonzero) digits is 64, while the sum is 14.

The square root of 21002441 is about 4582.8420221518. The cubic root of 21002441 is about 275.9031069603.

Adding to 21002441 its reverse (14420012), we get a palindrome (35422453).

The spelling of 21002441 in words is "twenty-one million, two thousand, four hundred forty-one".