21020052 has 12 divisors (see below), whose sum is σ = 49046816. Its totient is φ = 7006680.

The previous prime is 21020039. The next prime is 21020053. The reversal of 21020052 is 25002012.

It is a tau number, because it is divible by the number of its divisors (12).

It is a Harshad number since it is a multiple of its sum of digits (12), and also a Moran number because the ratio is a prime number: 1751671 = 21020052 / (2 + 1 + 0 + 2 + 0 + 0 + 5 + 2).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020053) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 875824 + ... + 875847.

Almost surely, 2^21020052 is an apocalyptic number.

It is an amenable number.

21020052 is an abundant number, since it is smaller than the sum of its proper divisors (28026764).

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

21020052 is a wasteful number, since it uses less digits than its factorization.

21020052 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1751678 (or 1751676 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 12.

The square root of 21020052 is about 4584.7630255009. The cubic root of 21020052 is about 275.9802023186.

Adding to 21020052 its reverse (25002012), we get a palindrome (46022064).

The spelling of 21020052 in words is "twenty-one million, twenty thousand, fifty-two".