21040642 has 32 divisors (see below), whose sum is σ = 37428480. Its totient is φ = 8683200.

The previous prime is 21040633. The next prime is 21040651. The reversal of 21040642 is 24604012.

It is an interprime number because it is at equal distance from previous prime (21040633) and next prime (21040651).

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 78084 + ... + 78352.

It is an arithmetic number, because the mean of its divisors is an integer number (1169640).

Almost surely, 2^21040642 is an apocalyptic number.

21040642 is a deficient number, since it is larger than the sum of its proper divisors (16387838).

21040642 is a wasteful number, since it uses less digits than its factorization.

21040642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 466.

The product of its (nonzero) digits is 384, while the sum is 19.

The square root of 21040642 is about 4587.0079572636. The cubic root of 21040642 is about 276.0702842078.

Adding to 21040642 its reverse (24604012), we get a palindrome (45644654).

The spelling of 21040642 in words is "twenty-one million, forty thousand, six hundred forty-two".