21066940 has 12 divisors (see below), whose sum is σ = 44240616. Its totient is φ = 8426768.

The previous prime is 21066937. The next prime is 21066959. The reversal of 21066940 is 4966012.

It is a junction number, because it is equal to n+sod(n) for n = 21066899 and 21066908.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 526654 + ... + 526693.

It is an arithmetic number, because the mean of its divisors is an integer number (3686718).

Almost surely, 2^21066940 is an apocalyptic number.

21066940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21066940 is an abundant number, since it is smaller than the sum of its proper divisors (23173676).

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

21066940 is a wasteful number, since it uses less digits than its factorization.

21066940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1053356 (or 1053354 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 28.

The square root of 21066940 is about 4589.8736366048. The cubic root of 21066940 is about 276.1852533505.

The spelling of 21066940 in words is "twenty-one million, sixty-six thousand, nine hundred forty".