21902 has 8 divisors (see below), whose sum is σ = 33696. Its totient is φ = 10672.

The previous prime is 21893. The next prime is 21911. The reversal of 21902 is 20912.

It is an interprime number because it is at equal distance from previous prime (21893) and next prime (21911).

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

It is a plaindrome in base 16.

It is a congruent number.

It is an unprimeable number.

21902 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 23 + ... + 210.

It is an arithmetic number, because the mean of its divisors is an integer number (4212).

2²¹⁹⁰² is an apocalyptic number.

21902 is a deficient number, since it is larger than the sum of its proper divisors (11794).

21902 is a wasteful number, since it uses less digits than its factorization.

21902 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 282.

The product of its (nonzero) digits is 36, while the sum is 14.

The square root of 21902 is about 147.9932430890. The cubic root of 21902 is about 27.9787253360.

Subtracting from 21902 its reverse (20912), we obtain a triangular number (990 = T₄₄).

The spelling of 21902 in words is "twenty-one thousand, nine hundred two".