21040867 has 4 divisors (see below), whose sum is σ = 21146800. Its totient is φ = 20934936.

The previous prime is 21040807. The next prime is 21040879. The reversal of 21040867 is 76804012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21040867 is a prime.

It is a super-2 number, since 2×21040867² = 885436168223378, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21040807) 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 3 ways as a sum of consecutive naturals, for example, 52668 + ... + 53065.

It is an arithmetic number, because the mean of its divisors is an integer number (5286700).

Almost surely, 2^21040867 is an apocalyptic number.

21040867 is a deficient number, since it is larger than the sum of its proper divisors (105933).

21040867 is a wasteful number, since it uses less digits than its factorization.

21040867 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105932.

The product of its (nonzero) digits is 2688, while the sum is 28.

The square root of 21040867 is about 4587.0324829894. The cubic root of 21040867 is about 276.0712682651.

Adding to 21040867 its reverse (76804012), we get a palindrome (97844879).

The spelling of 21040867 in words is "twenty-one million, forty thousand, eight hundred sixty-seven".