21179851 has 32 divisors (see below), whose sum is σ = 28753920. Its totient is φ = 15098400.

The previous prime is 21179843. The next prime is 21179861. The reversal of 21179851 is 15897112.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21179851 - 2³ = 21179843 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21179861) 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 31 ways as a sum of consecutive naturals, for example, 45120 + ... + 45586.

It is an arithmetic number, because the mean of its divisors is an integer number (898560).

Almost surely, 2^21179851 is an apocalyptic number.

21179851 is a deficient number, since it is larger than the sum of its proper divisors (7574069).

21179851 is a wasteful number, since it uses less digits than its factorization.

21179851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 535.

The product of its digits is 5040, while the sum is 34.

The square root of 21179851 is about 4602.1572115694. The cubic root of 21179851 is about 276.6777913625.

The spelling of 21179851 in words is "twenty-one million, one hundred seventy-nine thousand, eight hundred fifty-one".