21081056 has 12 divisors (see below), whose sum is σ = 41503392. Its totient is φ = 10540512.

The previous prime is 21081043. The next prime is 21081061. The reversal of 21081056 is 65018012.

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 as a sum of consecutive naturals, namely, 329360 + ... + 329423.

It is an arithmetic number, because the mean of its divisors is an integer number (3458616).

Almost surely, 2^21081056 is an apocalyptic number.

It is an amenable number.

21081056 is a deficient number, since it is larger than the sum of its proper divisors (20422336).

21081056 is an equidigital number, since it uses as much as digits as its factorization.

21081056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 658793 (or 658785 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 23.

The square root of 21081056 is about 4591.4111120657. The cubic root of 21081056 is about 276.2469259774.

Adding to 21081056 its reverse (65018012), we get a palindrome (86099068).

The spelling of 21081056 in words is "twenty-one million, eighty-one thousand, fifty-six".