21040641 has 12 divisors (see below), whose sum is σ = 31518032. Its totient is φ = 14026932.

The previous prime is 21040633. The next prime is 21040651. The reversal of 21040641 is 14604012.

21040641 is a `hidden beast` number, since 21 + 0 + 4 + 0 + 641 = 666.

It is not a de Polignac number, because 21040641 - 2³ = 21040633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21040601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 43051 + ... + 43536.

Almost surely, 2^21040641 is an apocalyptic number.

It is an amenable number.

21040641 is a deficient number, since it is larger than the sum of its proper divisors (10477391).

21040641 is an frugal number, since it uses more digits than its factorization.

21040641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86602 (or 86590 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 21040641 is about 4587.0078482601. The cubic root of 21040641 is about 276.0702798342.

Adding to 21040641 its reverse (14604012), we get a palindrome (35644653).

The spelling of 21040641 in words is "twenty-one million, forty thousand, six hundred forty-one".