21821708 has 12 divisors (see below), whose sum is σ = 38726352. Its totient is φ = 10757040.

The previous prime is 21821707. The next prime is 21821729. The reversal of 21821708 is 80712812.

It is not an unprimeable number, because it can be changed into a prime (21821707) 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, 38135 + ... + 38702.

It is an arithmetic number, because the mean of its divisors is an integer number (3227196).

Almost surely, 2^21821708 is an apocalyptic number.

It is an amenable number.

21821708 is a deficient number, since it is larger than the sum of its proper divisors (16904644).

21821708 is a wasteful number, since it uses less digits than its factorization.

21821708 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76912 (or 76910 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 29.

The square root of 21821708 is about 4671.3711049327. The cubic root of 21821708 is about 279.4449378062. Note that the first 3 decimals are identical.

The spelling of 21821708 in words is "twenty-one million, eight hundred twenty-one thousand, seven hundred eight".