21409475 has 24 divisors (see below), whose sum is σ = 27446160. Its totient is φ = 16560000.

The previous prime is 21409471. The next prime is 21409483. The reversal of 21409475 is 57490412.

It is a happy number.

It is not a de Polignac number, because 21409475 - 2² = 21409471 is a prime.

It is a Smith number, since the sum of its digits (32) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (21409471) 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, 153956 + ... + 154094.

It is an arithmetic number, because the mean of its divisors is an integer number (1143590).

Almost surely, 2^21409475 is an apocalyptic number.

21409475 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21409475 is a deficient number, since it is larger than the sum of its proper divisors (6036685).

21409475 is a wasteful number, since it uses less digits than its factorization.

21409475 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 311 (or 306 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 21409475 is about 4627.0373890860. The cubic root of 21409475 is about 277.6740784772.

Adding to 21409475 its reverse (57490412), we get a palindrome (78899887).

The spelling of 21409475 in words is "twenty-one million, four hundred nine thousand, four hundred seventy-five".