21142851 has 4 divisors (see below), whose sum is σ = 28190472. Its totient is φ = 14095232.

The previous prime is 21142831. The next prime is 21142859. The reversal of 21142851 is 15824112.

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 21142851 - 2⁶ = 21142787 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21142859) 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 3 ways as a sum of consecutive naturals, for example, 3523806 + ... + 3523811.

It is an arithmetic number, because the mean of its divisors is an integer number (7047618).

Almost surely, 2^21142851 is an apocalyptic number.

21142851 is a deficient number, since it is larger than the sum of its proper divisors (7047621).

21142851 is an equidigital number, since it uses as much as digits as its factorization.

21142851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7047620.

The product of its digits is 640, while the sum is 24.

The square root of 21142851 is about 4598.1356004363. The cubic root of 21142851 is about 276.5165839761.

Adding to 21142851 its reverse (15824112), we get a palindrome (36966963).

The spelling of 21142851 in words is "twenty-one million, one hundred forty-two thousand, eight hundred fifty-one".