21051646 has 32 divisors (see below), whose sum is σ = 39610368. Its totient is φ = 8151840.

The previous prime is 21051643. The next prime is 21051673. The reversal of 21051646 is 64615012.

It is a self number, because there is not a number n which added to its sum of digits gives 21051646.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21051643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 34036 + ... + 34648.

It is an arithmetic number, because the mean of its divisors is an integer number (1237824).

Almost surely, 2^21051646 is an apocalyptic number.

21051646 is a deficient number, since it is larger than the sum of its proper divisors (18558722).

21051646 is a wasteful number, since it uses less digits than its factorization.

21051646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 856.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 21051646 is about 4588.2072751784. The cubic root of 21051646 is about 276.1184029545.

Adding to 21051646 its reverse (64615012), we get a palindrome (85666658).

The spelling of 21051646 in words is "twenty-one million, fifty-one thousand, six hundred forty-six".