21683842 has 4 divisors (see below), whose sum is σ = 32525766. Its totient is φ = 10841920.

The previous prime is 21683839. The next prime is 21683843. The reversal of 21683842 is 24838612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 12737761 + 8946081 = 3569^2 + 2991^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21683798 and 21683807.

It is not an unprimeable number, because it can be changed into a prime (21683843) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5420959 + ... + 5420962.

Almost surely, 2^21683842 is an apocalyptic number.

21683842 is a deficient number, since it is larger than the sum of its proper divisors (10841924).

21683842 is a wasteful number, since it uses less digits than its factorization.

21683842 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10841923.

The product of its digits is 18432, while the sum is 34.

The square root of 21683842 is about 4656.5912425292. The cubic root of 21683842 is about 278.8551982168.

The spelling of 21683842 in words is "twenty-one million, six hundred eighty-three thousand, eight hundred forty-two".