21040475 has 24 divisors (see below), whose sum is σ = 28533888. Its totient is φ = 15321600.

The previous prime is 21040463. The next prime is 21040489. The reversal of 21040475 is 57404012.

It is a de Polignac number, because none of the positive numbers 2^k-21040475 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21040475.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 12377 + ... + 13973.

It is an arithmetic number, because the mean of its divisors is an integer number (1188912).

Almost surely, 2^21040475 is an apocalyptic number.

21040475 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21040475 is a deficient number, since it is larger than the sum of its proper divisors (7493413).

21040475 is a wasteful number, since it uses less digits than its factorization.

21040475 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1655 (or 1650 counting only the distinct ones).

The product of its (nonzero) digits is 1120, while the sum is 23.

The square root of 21040475 is about 4586.9897536402. The cubic root of 21040475 is about 276.0695538141.

Adding to 21040475 its reverse (57404012), we get a palindrome (78444487).

The spelling of 21040475 in words is "twenty-one million, forty thousand, four hundred seventy-five".