21159638 has 4 divisors (see below), whose sum is σ = 31739460. Its totient is φ = 10579818.

The previous prime is 21159631. The next prime is 21159641. The reversal of 21159638 is 83695112.

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

It is a junction number, because it is equal to n+sod(n) for n = 21159598 and 21159607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21159631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5289908 + ... + 5289911.

It is an arithmetic number, because the mean of its divisors is an integer number (7934865).

Almost surely, 2^21159638 is an apocalyptic number.

21159638 is a deficient number, since it is larger than the sum of its proper divisors (10579822).

21159638 is a wasteful number, since it uses less digits than its factorization.

21159638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10579821.

The product of its digits is 12960, while the sum is 35.

The square root of 21159638 is about 4599.9606520056. The cubic root of 21159638 is about 276.5897474915.

The spelling of 21159638 in words is "twenty-one million, one hundred fifty-nine thousand, six hundred thirty-eight".