21641020 has 24 divisors (see below), whose sum is σ = 45534384. Its totient is φ = 8639616.

The previous prime is 21641003. The next prime is 21641027. The reversal of 21641020 is 2014612.

It is a junction number, because it is equal to n+sod(n) for n = 21640985 and 21641003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21641027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17544 + ... + 18736.

It is an arithmetic number, because the mean of its divisors is an integer number (1897266).

Almost surely, 2^21641020 is an apocalyptic number.

21641020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21641020 is an abundant number, since it is smaller than the sum of its proper divisors (23893364).

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

21641020 is a wasteful number, since it uses less digits than its factorization.

21641020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2109 (or 2107 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 21641020 is about 4651.9909716163. The cubic root of 21641020 is about 278.6715129560.

Adding to 21641020 its reverse (2014612), we get a palindrome (23655632).

The spelling of 21641020 in words is "twenty-one million, six hundred forty-one thousand, twenty".