21110405 has 8 divisors (see below), whose sum is σ = 26206200. Its totient is φ = 16305856.

The previous prime is 21110393. The next prime is 21110423. The reversal of 21110405 is 50401112.

It can be written as a sum of positive squares in 4 ways, for example, as 33124 + 21077281 = 182^2 + 4591^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21110405 - 2⁸ = 21110149 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21110405.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 72650 + ... + 72939.

It is an arithmetic number, because the mean of its divisors is an integer number (3275775).

Almost surely, 2^21110405 is an apocalyptic number.

It is an amenable number.

21110405 is a deficient number, since it is larger than the sum of its proper divisors (5095795).

21110405 is a wasteful number, since it uses less digits than its factorization.

21110405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 145623.

The product of its (nonzero) digits is 40, while the sum is 14.

The square root of 21110405 is about 4594.6060766947. The cubic root of 21110405 is about 276.3750633201.

Adding to 21110405 its reverse (50401112), we get a palindrome (71511517).

The spelling of 21110405 in words is "twenty-one million, one hundred ten thousand, four hundred five".