21283939 has 8 divisors (see below), whose sum is σ = 21631680. Its totient is φ = 20938536.

The previous prime is 21283931. The next prime is 21283967. The reversal of 21283939 is 93938212.

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

It is a cyclic number.

It is not a de Polignac number, because 21283939 - 2³ = 21283931 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21283898 and 21283907.

It is not an unprimeable number, because it can be changed into a prime (21283931) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28432 + ... + 29170.

It is an arithmetic number, because the mean of its divisors is an integer number (2703960).

Almost surely, 2^21283939 is an apocalyptic number.

21283939 is a deficient number, since it is larger than the sum of its proper divisors (347741).

21283939 is an equidigital number, since it uses as much as digits as its factorization.

21283939 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1169.

The product of its digits is 23328, while the sum is 37.

The square root of 21283939 is about 4613.4519613842. The cubic root of 21283939 is about 277.1302935891.

It can be divided in two parts, 212839 and 39, that added together give a triangular number (212878 = T₆₅₂).

The spelling of 21283939 in words is "twenty-one million, two hundred eighty-three thousand, nine hundred thirty-nine".