21417405 has 32 divisors (see below), whose sum is σ = 35354880. Its totient is φ = 11066880.

The previous prime is 21417377. The next prime is 21417437. The reversal of 21417405 is 50471412.

It is not a de Polignac number, because 21417405 - 2¹¹ = 21415357 is a prime.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 81304 + ... + 81566.

It is an arithmetic number, because the mean of its divisors is an integer number (1104840).

Almost surely, 2^21417405 is an apocalyptic number.

It is an amenable number.

21417405 is a deficient number, since it is larger than the sum of its proper divisors (13937475).

21417405 is a wasteful number, since it uses less digits than its factorization.

21417405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 421.

The product of its (nonzero) digits is 1120, while the sum is 24.

The square root of 21417405 is about 4627.8942295606. The cubic root of 21417405 is about 277.7083574376.

Adding to 21417405 its reverse (50471412), we get a palindrome (71888817).

The spelling of 21417405 in words is "twenty-one million, four hundred seventeen thousand, four hundred five".