21821512 has 16 divisors (see below), whose sum is σ = 41913900. Its totient is φ = 10644480.

The previous prime is 21821507. The next prime is 21821533. The reversal of 21821512 is 21512812.

It can be written as a sum of positive squares in 2 ways, for example, as 21585316 + 236196 = 4646^2 + 486^2 .

It is a super-2 number, since 2×21821512² = 952356771932288, which contains 22 as substring.

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 3 ways as a sum of consecutive naturals, for example, 32937 + ... + 33592.

Almost surely, 2^21821512 is an apocalyptic number.

It is an amenable number.

21821512 is a deficient number, since it is larger than the sum of its proper divisors (20092388).

21821512 is a wasteful number, since it uses less digits than its factorization.

21821512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66576 (or 66572 counting only the distinct ones).

The product of its digits is 320, while the sum is 22.

The square root of 21821512 is about 4671.3501260342. The cubic root of 21821512 is about 279.4441011566. Note that the first 3 decimals are identical.

The spelling of 21821512 in words is "twenty-one million, eight hundred twenty-one thousand, five hundred twelve".