21229851 has 16 divisors (see below), whose sum is σ = 29661696. Its totient is φ = 13480896.

The previous prime is 21229847. The next prime is 21229867. The reversal of 21229851 is 15892212.

It is not a de Polignac number, because 21229851 - 2² = 21229847 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21229051) 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, 21106 + ... + 22088.

It is an arithmetic number, because the mean of its divisors is an integer number (1853856).

Almost surely, 2^21229851 is an apocalyptic number.

21229851 is a deficient number, since it is larger than the sum of its proper divisors (8431845).

21229851 is a wasteful number, since it uses less digits than its factorization.

21229851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1322.

The product of its digits is 2880, while the sum is 30.

The square root of 21229851 is about 4607.5862444451. The cubic root of 21229851 is about 276.8953411740.

The spelling of 21229851 in words is "twenty-one million, two hundred twenty-nine thousand, eight hundred fifty-one".