21040747 has 48 divisors (see below), whose sum is σ = 29302560. Its totient is φ = 14902272.

The previous prime is 21040741. The next prime is 21040759. The reversal of 21040747 is 74704012.

It is a de Polignac number, because none of the positive numbers 2^k-21040747 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21040741) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 314008 + ... + 314074.

It is an arithmetic number, because the mean of its divisors is an integer number (610470).

Almost surely, 2^21040747 is an apocalyptic number.

21040747 is a deficient number, since it is larger than the sum of its proper divisors (8261813).

21040747 is a wasteful number, since it uses less digits than its factorization.

21040747 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140 (or 133 counting only the distinct ones).

The product of its (nonzero) digits is 1568, while the sum is 25.

The square root of 21040747 is about 4587.0194026187. The cubic root of 21040747 is about 276.0707434354.

Adding to 21040747 its reverse (74704012), we get a palindrome (95744759).

The spelling of 21040747 in words is "twenty-one million, forty thousand, seven hundred forty-seven".