21066512 has 10 divisors (see below), whose sum is σ = 40816398. Its totient is φ = 10533248.

The previous prime is 21066511. The next prime is 21066523. The reversal of 21066512 is 21566012.

It can be written as a sum of positive squares in only one way, i.e., 20939776 + 126736 = 4576^2 + 356^2 .

It is a super-2 number, since 2×21066512² = 887595855692288, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21066511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 658313 + ... + 658344.

Almost surely, 2^21066512 is an apocalyptic number.

It is an amenable number.

21066512 is a deficient number, since it is larger than the sum of its proper divisors (19749886).

21066512 is a wasteful number, since it uses less digits than its factorization.

21066512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1316665 (or 1316659 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 21066512 is about 4589.8270119908. The cubic root of 21066512 is about 276.1833829936.

Subtracting 21066512 from its reverse (21566012), we obtain a triangular number (499500 = T₉₉₉).

The spelling of 21066512 in words is "twenty-one million, sixty-six thousand, five hundred twelve".