21470851 has 4 divisors (see below), whose sum is σ = 21496104. Its totient is φ = 21445600.

The previous prime is 21470843. The next prime is 21470899. The reversal of 21470851 is 15807412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21470851 - 2³ = 21470843 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21470821) 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 3 ways as a sum of consecutive naturals, for example, 11305 + ... + 13066.

It is an arithmetic number, because the mean of its divisors is an integer number (5374026).

Almost surely, 2^21470851 is an apocalyptic number.

21470851 is a deficient number, since it is larger than the sum of its proper divisors (25253).

21470851 is an equidigital number, since it uses as much as digits as its factorization.

21470851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25252.

The product of its (nonzero) digits is 2240, while the sum is 28.

The square root of 21470851 is about 4633.6649641509. The cubic root of 21470851 is about 277.9391677189.

The spelling of 21470851 in words is "twenty-one million, four hundred seventy thousand, eight hundred fifty-one".