21040623 has 24 divisors (see below), whose sum is σ = 31187520. Its totient is φ = 13665600.

The previous prime is 21040601. The next prime is 21040627. The reversal of 21040623 is 32604012.

It is a happy number.

21040623 is a `hidden beast` number, since 2 + 1 + 0 + 40 + 623 = 666.

It is not a de Polignac number, because 21040623 - 2⁶ = 21040559 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21040596 and 21040605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21040627) 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 23 ways as a sum of consecutive naturals, for example, 71665 + ... + 71957.

It is an arithmetic number, because the mean of its divisors is an integer number (1299480).

Almost surely, 2^21040623 is an apocalyptic number.

21040623 is a deficient number, since it is larger than the sum of its proper divisors (10146897).

21040623 is a wasteful number, since it uses less digits than its factorization.

21040623 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 479 (or 476 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 21040623 is about 4587.0058861964. The cubic root of 21040623 is about 276.0702011093.

Adding to 21040623 its reverse (32604012), we get a palindrome (53644635).

The spelling of 21040623 in words is "twenty-one million, forty thousand, six hundred twenty-three".