21409075 has 12 divisors (see below), whose sum is σ = 26913208. Its totient is φ = 16891200.

The previous prime is 21409061. The next prime is 21409117. The reversal of 21409075 is 57090412.

It is a happy number.

It is not a de Polignac number, because 21409075 - 2⁵ = 21409043 is a prime.

It is a hoax number, since the sum of its digits (28) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 4041 + ... + 7690.

Almost surely, 2^21409075 is an apocalyptic number.

21409075 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21409075 is a deficient number, since it is larger than the sum of its proper divisors (5504133).

21409075 is a wasteful number, since it uses less digits than its factorization.

21409075 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11814 (or 11809 counting only the distinct ones).

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 21409075 is about 4626.9941646819. The cubic root of 21409075 is about 277.6723491756.

Adding to 21409075 its reverse (57090412), we get a palindrome (78499487).

The spelling of 21409075 in words is "twenty-one million, four hundred nine thousand, seventy-five".