21857142 has 16 divisors (see below), whose sum is σ = 44367552. Its totient is φ = 7176840.

The previous prime is 21857131. The next prime is 21857161. The reversal of 21857142 is 24175812.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 26784 + ... + 27587.

It is an arithmetic number, because the mean of its divisors is an integer number (2772972).

Almost surely, 2^21857142 is an apocalyptic number.

21857142 is an abundant number, since it is smaller than the sum of its proper divisors (22510410).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21857142 is a wasteful number, since it uses less digits than its factorization.

21857142 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54443.

The product of its digits is 4480, while the sum is 30.

The square root of 21857142 is about 4675.1622431740. The cubic root of 21857142 is about 279.5961098597.

The spelling of 21857142 in words is "twenty-one million, eight hundred fifty-seven thousand, one hundred forty-two".