21020412 has 48 divisors (see below), whose sum is σ = 57209600. Its totient is φ = 6004656.

The previous prime is 21020411. The next prime is 21020429. The reversal of 21020412 is 21402012.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020411) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1563 + ... + 6669.

Almost surely, 2^21020412 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21020412, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28604800).

21020412 is an abundant number, since it is smaller than the sum of its proper divisors (36189188).

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

21020412 is a wasteful number, since it uses less digits than its factorization.

21020412 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5135 (or 5119 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 12.

The square root of 21020412 is about 4584.8022858134. The cubic root of 21020412 is about 275.9817778350.

Adding to 21020412 its reverse (21402012), we get a palindrome (42422424).

The spelling of 21020412 in words is "twenty-one million, twenty thousand, four hundred twelve".