21020536 has 32 divisors (see below), whose sum is σ = 42512400. Its totient is φ = 9711360.

The previous prime is 21020533. The next prime is 21020537. The reversal of 21020536 is 63502012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020533) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4546 + ... + 7918.

Almost surely, 2^21020536 is an apocalyptic number.

It is an amenable number.

21020536 is an abundant number, since it is smaller than the sum of its proper divisors (21491864).

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

21020536 is a wasteful number, since it uses less digits than its factorization.

21020536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3439 (or 3435 counting only the distinct ones).

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

The square root of 21020536 is about 4584.8158087321. The cubic root of 21020536 is about 275.9823205087.

Adding to 21020536 its reverse (63502012), we get a palindrome (84522548).

The spelling of 21020536 in words is "twenty-one million, twenty thousand, five hundred thirty-six".