21080851 has 8 divisors (see below), whose sum is σ = 23030784. Its totient is φ = 19136520.

The previous prime is 21080849. The next prime is 21080869. The reversal of 21080851 is 15808012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21080851 - 2¹ = 21080849 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21080831) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 12670 + ... + 14236.

It is an arithmetic number, because the mean of its divisors is an integer number (2878848).

Almost surely, 2^21080851 is an apocalyptic number.

21080851 is a deficient number, since it is larger than the sum of its proper divisors (1949933).

21080851 is a wasteful number, since it uses less digits than its factorization.

21080851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2801.

The product of its (nonzero) digits is 640, while the sum is 25.

The square root of 21080851 is about 4591.3887877199. The cubic root of 21080851 is about 276.2460305320.

Adding to 21080851 its reverse (15808012), we get a palindrome (36888863).

The spelling of 21080851 in words is "twenty-one million, eighty thousand, eight hundred fifty-one".