21040063 has 4 divisors (see below), whose sum is σ = 22952808. Its totient is φ = 19127320.

The previous prime is 21040057. The next prime is 21040073. The reversal of 21040063 is 36004012.

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-21040063 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21040043) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 956356 + ... + 956377.

It is an arithmetic number, because the mean of its divisors is an integer number (5738202).

Almost surely, 2^21040063 is an apocalyptic number.

21040063 is a deficient number, since it is larger than the sum of its proper divisors (1912745).

21040063 is a wasteful number, since it uses less digits than its factorization.

21040063 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1912744.

The product of its (nonzero) digits is 144, while the sum is 16.

The square root of 21040063 is about 4586.9448437931. The cubic root of 21040063 is about 276.0677518681.

Adding to 21040063 its reverse (36004012), we get a palindrome (57044075).

The spelling of 21040063 in words is "twenty-one million, forty thousand, sixty-three".