21650 has 12 divisors (see below), whose sum is σ = 40362. Its totient is φ = 8640.

The previous prime is 21649. The next prime is 21661. The reversal of 21650 is 5612.

It can be written as a sum of positive squares in 3 ways, for example, as 11449 + 10201 = 107^2 + 101^2 .

It is an alternating number because its digits alternate between even and odd.

It is a nialpdrome in base 8.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 167 + ... + 266.

2²¹⁶⁵⁰ is an apocalyptic number.

21650 is a deficient number, since it is larger than the sum of its proper divisors (18712).

21650 is a wasteful number, since it uses less digits than its factorization.

21650 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 445 (or 440 counting only the distinct ones).

The product of its (nonzero) digits is 60, while the sum is 14.

The square root of 21650 is about 147.1393896956. The cubic root of 21650 is about 27.8710052793.

The spelling of 21650 in words is "twenty-one thousand, six hundred fifty".