21768900 has 72 divisors (see below), whose sum is σ = 63537600. Its totient is φ = 5754240.

The previous prime is 21768893. The next prime is 21768911. The reversal of 21768900 is 986712.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 44457 + ... + 44943.

Almost surely, 2^21768900 is an apocalyptic number.

21768900 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21768900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31768800).

21768900 is an abundant number, since it is smaller than the sum of its proper divisors (41768700).

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

21768900 is a wasteful number, since it uses less digits than its factorization.

21768900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 653 (or 646 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 33.

The square root of 21768900 is about 4665.7153792318. The cubic root of 21768900 is about 279.2193390873.

The spelling of 21768900 in words is "twenty-one million, seven hundred sixty-eight thousand, nine hundred".