21020432 has 40 divisors (see below), whose sum is σ = 43579800. Its totient is φ = 9787392.

The previous prime is 21020431. The next prime is 21020437. The reversal of 21020432 is 23402012.

It can be written as a sum of positive squares in 4 ways, for example, as 3748096 + 17272336 = 1936^2 + 4156^2 .

It is a super-2 number, since 2×21020432² = 883717122933248, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21020431) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 29294 + ... + 30002.

It is an arithmetic number, because the mean of its divisors is an integer number (1089495).

Almost surely, 2^21020432 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 21020432, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21789900).

21020432 is an abundant number, since it is smaller than the sum of its proper divisors (22559368).

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

21020432 is a wasteful number, since it uses less digits than its factorization.

21020432 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 843 (or 837 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 14.

The square root of 21020432 is about 4584.8044669320. The cubic root of 21020432 is about 275.9818653631.

Adding to 21020432 its reverse (23402012), we get a palindrome (44422444).

The spelling of 21020432 in words is "twenty-one million, twenty thousand, four hundred thirty-two".