21180705 has 64 divisors (see below), whose sum is σ = 42577920. Its totient is φ = 8752896.

The previous prime is 21180703. The next prime is 21180707. The reversal of 21180705 is 50708112.

It is an interprime number because it is at equal distance from previous prime (21180703) and next prime (21180707).

It is not a de Polignac number, because 21180705 - 2¹ = 21180703 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21180703) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 80404 + ... + 80666.

It is an arithmetic number, because the mean of its divisors is an integer number (665280).

Almost surely, 2^21180705 is an apocalyptic number.

It is an amenable number.

21180705 is an abundant number, since it is smaller than the sum of its proper divisors (21397215).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21180705 is a wasteful number, since it uses less digits than its factorization.

21180705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 350.

The product of its (nonzero) digits is 560, while the sum is 24.

The square root of 21180705 is about 4602.2499932098. The cubic root of 21180705 is about 276.6815099857.

Adding to 21180705 its reverse (50708112), we get a palindrome (71888817).

The spelling of 21180705 in words is "twenty-one million, one hundred eighty thousand, seven hundred five".