21005735 has 16 divisors (see below), whose sum is σ = 27185760. Its totient is φ = 15528960.

The previous prime is 21005713. The next prime is 21005737. The reversal of 21005735 is 53750012.

It is a de Polignac number, because none of the positive numbers 2^k-21005735 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21005735.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21005737) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1199 + ... + 6591.

It is an arithmetic number, because the mean of its divisors is an integer number (1699110).

Almost surely, 2^21005735 is an apocalyptic number.

21005735 is a deficient number, since it is larger than the sum of its proper divisors (6180025).

21005735 is a wasteful number, since it uses less digits than its factorization.

21005735 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5458.

The product of its (nonzero) digits is 1050, while the sum is 23.

The square root of 21005735 is about 4583.2013920403. The cubic root of 21005735 is about 275.9175303207.

Adding to 21005735 its reverse (53750012), we get a palindrome (74755747).

The spelling of 21005735 in words is "twenty-one million, five thousand, seven hundred thirty-five".