21020635 has 8 divisors (see below), whose sum is σ = 26038656. Its totient is φ = 16273920.

The previous prime is 21020633. The next prime is 21020641. The reversal of 21020635 is 53602012.

It is a happy number.

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

It is not a de Polignac number, because 21020635 - 2¹ = 21020633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21020633) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 67654 + ... + 67963.

It is an arithmetic number, because the mean of its divisors is an integer number (3254832).

Almost surely, 2^21020635 is an apocalyptic number.

21020635 is a deficient number, since it is larger than the sum of its proper divisors (5018021).

21020635 is a wasteful number, since it uses less digits than its factorization.

21020635 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 135653.

The product of its (nonzero) digits is 360, while the sum is 19.

The square root of 21020635 is about 4584.8266052273. The cubic root of 21020635 is about 275.9827537708.

Adding to 21020635 its reverse (53602012), we get a palindrome (74622647).

The spelling of 21020635 in words is "twenty-one million, twenty thousand, six hundred thirty-five".