21861838 has 8 divisors (see below), whose sum is σ = 32819688. Its totient is φ = 10921944.

The previous prime is 21861817. The next prime is 21861839. The reversal of 21861838 is 83816812.

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

It is a junction number, because it is equal to n+sod(n) for n = 21861797 and 21861806.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21861839) 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, 856 + ... + 6667.

It is an arithmetic number, because the mean of its divisors is an integer number (4102461).

Almost surely, 2^21861838 is an apocalyptic number.

21861838 is a deficient number, since it is larger than the sum of its proper divisors (10957850).

21861838 is a wasteful number, since it uses less digits than its factorization.

21861838 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8978.

The product of its digits is 18432, while the sum is 37.

The square root of 21861838 is about 4675.6644447608. The cubic root of 21861838 is about 279.6161321376.

The spelling of 21861838 in words is "twenty-one million, eight hundred sixty-one thousand, eight hundred thirty-eight".