21610005 has 16 divisors (see below), whose sum is σ = 34680960. Its totient is φ = 11490368.

The previous prime is 21610003. The next prime is 21610019. The reversal of 21610005 is 50001612.

It is a cyclic number.

It is not a de Polignac number, because 21610005 - 2¹ = 21610003 is a prime.

It is a super-2 number, since 2×21610005² = 933984632200050, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21610003) 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 15 ways as a sum of consecutive naturals, for example, 3379 + ... + 7391.

It is an arithmetic number, because the mean of its divisors is an integer number (2167560).

Almost surely, 2^21610005 is an apocalyptic number.

It is an amenable number.

21610005 is a deficient number, since it is larger than the sum of its proper divisors (13070955).

21610005 is a wasteful number, since it uses less digits than its factorization.

21610005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4380.

The product of its (nonzero) digits is 60, while the sum is 15.

The square root of 21610005 is about 4648.6562574576. The cubic root of 21610005 is about 278.5383225427.

Adding to 21610005 its reverse (50001612), we get a palindrome (71611617).

The spelling of 21610005 in words is "twenty-one million, six hundred ten thousand, five".