21059653 has 4 divisors (see below), whose sum is σ = 21143808. Its totient is φ = 20975500.

The previous prime is 21059629. The next prime is 21059669. The reversal of 21059653 is 35695012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21059653 - 2¹³ = 21051461 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21059453) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 41701 + ... + 42202.

It is an arithmetic number, because the mean of its divisors is an integer number (5285952).

Almost surely, 2^21059653 is an apocalyptic number.

It is an amenable number.

21059653 is a deficient number, since it is larger than the sum of its proper divisors (84155).

21059653 is an equidigital number, since it uses as much as digits as its factorization.

21059653 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84154.

The product of its (nonzero) digits is 8100, while the sum is 31.

The square root of 21059653 is about 4589.0797552451. The cubic root of 21059653 is about 276.1534057568.

It can be divided in two parts, 21059 and 653, that added together give a palindrome (21712).

The spelling of 21059653 in words is "twenty-one million, fifty-nine thousand, six hundred fifty-three".