21066420 has 48 divisors (see below), whose sum is σ = 59189760. Its totient is φ = 5598336.

The previous prime is 21066403. The next prime is 21066443. The reversal of 21066420 is 2466012.

It is a happy number.

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 15 ways as a sum of consecutive naturals, for example, 28374 + ... + 29106.

It is an arithmetic number, because the mean of its divisors is an integer number (1233120).

Almost surely, 2^21066420 is an apocalyptic number.

21066420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21066420 is an abundant number, since it is smaller than the sum of its proper divisors (38123340).

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

21066420 is a wasteful number, since it uses less digits than its factorization.

21066420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1224 (or 1222 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 21.

The square root of 21066420 is about 4589.8169898156. The cubic root of 21066420 is about 276.1829809509.

The spelling of 21066420 in words is "twenty-one million, sixty-six thousand, four hundred twenty".