21022680 has 128 divisors (see below), whose sum is σ = 74649600. Its totient is φ = 4634112.

The previous prime is 21022669. The next prime is 21022699. The reversal of 21022680 is 8622012.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 23929 + ... + 24791.

It is an arithmetic number, because the mean of its divisors is an integer number (583200).

Almost surely, 2^21022680 is an apocalyptic number.

21022680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21022680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37324800).

21022680 is an abundant number, since it is smaller than the sum of its proper divisors (53626920).

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

21022680 is a wasteful number, since it uses less digits than its factorization.

21022680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 913 (or 909 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 21022680 is about 4585.0496180521. The cubic root of 21022680 is about 275.9917031742.

Adding to 21022680 its reverse (8622012), we get a palindrome (29644692).

The spelling of 21022680 in words is "twenty-one million, twenty-two thousand, six hundred eighty".