21129382 has 4 divisors (see below), whose sum is σ = 31694076. Its totient is φ = 10564690.

The previous prime is 21129379. The next prime is 21129403. The reversal of 21129382 is 28392112.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21129382.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5282344 + ... + 5282347.

It is an arithmetic number, because the mean of its divisors is an integer number (7923519).

Almost surely, 2^21129382 is an apocalyptic number.

21129382 is a deficient number, since it is larger than the sum of its proper divisors (10564694).

21129382 is a wasteful number, since it uses less digits than its factorization.

21129382 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10564693.

The product of its digits is 1728, while the sum is 28.

The square root of 21129382 is about 4596.6707517507. The cubic root of 21129382 is about 276.4578534384.

The spelling of 21129382 in words is "twenty-one million, one hundred twenty-nine thousand, three hundred eighty-two".