21040807 has 2 divisors, whose sum is σ = 21040808. Its totient is φ = 21040806.

The previous prime is 21040787. The next prime is 21040879. The reversal of 21040807 is 70804012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21040807 - 2¹⁹ = 20516519 is a prime.

It is a super-2 number, since 2×21040807² = 885431118422498, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21040007) 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 as a sum of consecutive naturals, namely, 10520403 + 10520404.

It is an arithmetic number, because the mean of its divisors is an integer number (10520404).

Almost surely, 2^21040807 is an apocalyptic number.

21040807 is a deficient number, since it is larger than the sum of its proper divisors (1).

21040807 is an equidigital number, since it uses as much as digits as its factorization.

21040807 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 448, while the sum is 22.

The square root of 21040807 is about 4587.0259428087. The cubic root of 21040807 is about 276.0710058505.

Adding to 21040807 its reverse (70804012), we get a palindrome (91844819).

The spelling of 21040807 in words is "twenty-one million, forty thousand, eight hundred seven".