21857738 has 8 divisors (see below), whose sum is σ = 37470432. Its totient is φ = 9367596.

The previous prime is 21857723. The next prime is 21857747. The reversal of 21857738 is 83775812.

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 = 21857695 and 21857704.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 780620 + ... + 780647.

It is an arithmetic number, because the mean of its divisors is an integer number (4683804).

Almost surely, 2^21857738 is an apocalyptic number.

21857738 is a deficient number, since it is larger than the sum of its proper divisors (15612694).

21857738 is a wasteful number, since it uses less digits than its factorization.

21857738 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1561276.

The product of its digits is 94080, while the sum is 41.

The square root of 21857738 is about 4675.2259838429. The cubic root of 21857738 is about 279.5986511765.

The spelling of 21857738 in words is "twenty-one million, eight hundred fifty-seven thousand, seven hundred thirty-eight".