21857814 has 48 divisors (see below), whose sum is σ = 52223184. Its totient is φ = 6552000.

The previous prime is 21857813. The next prime is 21857819. The reversal of 21857814 is 41875812.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21857813) 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 23 ways as a sum of consecutive naturals, for example, 19452 + ... + 20544.

It is an arithmetic number, because the mean of its divisors is an integer number (1087983).

Almost surely, 2^21857814 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21857814, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26111592).

21857814 is an abundant number, since it is smaller than the sum of its proper divisors (30365370).

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

21857814 is a wasteful number, since it uses less digits than its factorization.

21857814 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1213 (or 1210 counting only the distinct ones).

The product of its digits is 17920, while the sum is 36.

The square root of 21857814 is about 4675.2341117852. The cubic root of 21857814 is about 279.5989752337.

It can be divided in two parts, 2185 and 7814, that added together give a palindrome (9999).

The spelling of 21857814 in words is "twenty-one million, eight hundred fifty-seven thousand, eight hundred fourteen".