21243908 has 12 divisors (see below), whose sum is σ = 42487872. Its totient is φ = 9104520.

The previous prime is 21243907. The next prime is 21243913. The reversal of 21243908 is 80934212.

21243908 is an admirable number.

It is a super-3 number, since 3×21243908³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (21243907) 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, 379328 + ... + 379383.

It is an arithmetic number, because the mean of its divisors is an integer number (3540656).

Almost surely, 2^21243908 is an apocalyptic number.

21243908 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21243908 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21243908 is a wasteful number, since it uses less digits than its factorization.

21243908 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 758722 (or 758720 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 29.

The square root of 21243908 is about 4609.1114111074. Note that the first 3 decimals coincide. The cubic root of 21243908 is about 276.9564416036.

The spelling of 21243908 in words is "twenty-one million, two hundred forty-three thousand, nine hundred eight".