21032020 has 12 divisors (see below), whose sum is σ = 44167284. Its totient is φ = 8412800.

The previous prime is 21032003. The next prime is 21032023. The reversal of 21032020 is 2023012.

It can be written as a sum of positive squares in 2 ways, for example, as 15888196 + 5143824 = 3986^2 + 2268^2 .

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a junction number, because it is equal to n+sod(n) for n = 21031988 and 21032006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21032023) 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, 525781 + ... + 525820.

It is an arithmetic number, because the mean of its divisors is an integer number (3680607).

Almost surely, 2^21032020 is an apocalyptic number.

21032020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21032020 is an abundant number, since it is smaller than the sum of its proper divisors (23135264).

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

21032020 is a wasteful number, since it uses less digits than its factorization.

21032020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1051610 (or 1051608 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 10.

The square root of 21032020 is about 4586.0680326397. The cubic root of 21032020 is about 276.0325698454.

Adding to 21032020 its reverse (2023012), we get a palindrome (23055032).

The spelling of 21032020 in words is "twenty-one million, thirty-two thousand, twenty".