21862 has 8 divisors (see below), whose sum is σ = 34776. Its totient is φ = 10272.

The previous prime is 21859. The next prime is 21863. The reversal of 21862 is 26812.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a plaindrome in base 16.

It is a zygodrome in base 5 and base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21863) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 288 + ... + 355.

It is an arithmetic number, because the mean of its divisors is an integer number (4347).

2²¹⁸⁶² is an apocalyptic number.

21862 is a deficient number, since it is larger than the sum of its proper divisors (12914).

21862 is a wasteful number, since it uses less digits than its factorization.

21862 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 662.

The product of its digits is 192, while the sum is 19.

The square root of 21862 is about 147.8580400249. The cubic root of 21862 is about 27.9616822804.

Subtracting 21862 from its reverse (26812), we obtain a triangular number (4950 = T₉₉).

The spelling of 21862 in words is "twenty-one thousand, eight hundred sixty-two".