21050664 has 16 divisors (see below), whose sum is σ = 52626720. Its totient is φ = 7016880.

The previous prime is 21050629. The next prime is 21050677. The reversal of 21050664 is 46605012.

It is a Harshad number since it is a multiple of its sum of digits (24), and also a Moran number because the ratio is a prime number: 877111 = 21050664 / (2 + 1 + 0 + 5 + 0 + 6 + 6 + 4).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 438532 + ... + 438579.

It is an arithmetic number, because the mean of its divisors is an integer number (3289170).

Almost surely, 2^21050664 is an apocalyptic number.

21050664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21050664 is an abundant number, since it is smaller than the sum of its proper divisors (31576056).

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

21050664 is a wasteful number, since it uses less digits than its factorization.

21050664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 877120 (or 877116 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 24.

The square root of 21050664 is about 4588.1002604564. The cubic root of 21050664 is about 276.1141095058.

Adding to 21050664 its reverse (46605012), we get a palindrome (67655676).

The spelling of 21050664 in words is "twenty-one million, fifty thousand, six hundred sixty-four".