21291382 has 32 divisors (see below), whose sum is σ = 38203200. Its totient is φ = 8890560.

The previous prime is 21291373. The next prime is 21291383. The reversal of 21291382 is 28319212.

It is a self number, because there is not a number n which added to its sum of digits gives 21291382.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21291383) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27748 + ... + 28504.

It is an arithmetic number, because the mean of its divisors is an integer number (1193850).

Almost surely, 2^21291382 is an apocalyptic number.

21291382 is a deficient number, since it is larger than the sum of its proper divisors (16911818).

21291382 is an equidigital number, since it uses as much as digits as its factorization.

21291382 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 821 (or 807 counting only the distinct ones).

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

The square root of 21291382 is about 4614.2585536573. The cubic root of 21291382 is about 277.1625940071.

The spelling of 21291382 in words is "twenty-one million, two hundred ninety-one thousand, three hundred eighty-two".