21036653 has 4 divisors (see below), whose sum is σ = 22949088. Its totient is φ = 19124220.

The previous prime is 21036647. The next prime is 21036671. The reversal of 21036653 is 35663012.

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 21036653 - 2⁴ = 21036637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21036623) 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, 956201 + ... + 956222.

It is an arithmetic number, because the mean of its divisors is an integer number (5737272).

Almost surely, 2^21036653 is an apocalyptic number.

It is an amenable number.

21036653 is a deficient number, since it is larger than the sum of its proper divisors (1912435).

21036653 is a wasteful number, since it uses less digits than its factorization.

21036653 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1912434.

The product of its (nonzero) digits is 3240, while the sum is 26.

The square root of 21036653 is about 4586.5731216236. The cubic root of 21036653 is about 276.0528368003.

Adding to 21036653 its reverse (35663012), we get a palindrome (56699665).

It can be divided in two parts, 210 and 36653, that added together give a palindrome (36863).

The spelling of 21036653 in words is "twenty-one million, thirty-six thousand, six hundred fifty-three".