20921020 has 12 divisors (see below), whose sum is σ = 43934184. Its totient is φ = 8368400.

The previous prime is 20921009. The next prime is 20921023. The reversal of 20921020 is 2012902.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 20920985 and 20921003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20921023) 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, 523006 + ... + 523045.

It is an arithmetic number, because the mean of its divisors is an integer number (3661182).

Almost surely, 2^20921020 is an apocalyptic number.

20921020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20921020 is an abundant number, since it is smaller than the sum of its proper divisors (23013164).

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

20921020 is a wasteful number, since it uses less digits than its factorization.

20921020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1046060 (or 1046058 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 20921020 is about 4573.9501527673. The cubic root of 20921020 is about 275.5461103779.

Adding to 20921020 its reverse (2012902), we get a palindrome (22933922).

The spelling of 20921020 in words is "twenty million, nine hundred twenty-one thousand, twenty".