21966728 has 16 divisors (see below), whose sum is σ = 47071680. Its totient is φ = 9414288.

The previous prime is 21966727. The next prime is 21966731. The reversal of 21966728 is 82766912.

It is not an unprimeable number, because it can be changed into a prime (21966727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 196076 + ... + 196187.

It is an arithmetic number, because the mean of its divisors is an integer number (2941980).

Almost surely, 2^21966728 is an apocalyptic number.

21966728 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21966728 is an abundant number, since it is smaller than the sum of its proper divisors (25104952).

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

21966728 is a wasteful number, since it uses less digits than its factorization.

21966728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 392276 (or 392272 counting only the distinct ones).

The product of its digits is 72576, while the sum is 41.

The square root of 21966728 is about 4686.8676106756. The cubic root of 21966728 is about 280.0626050487.

The spelling of 21966728 in words is "twenty-one million, nine hundred sixty-six thousand, seven hundred twenty-eight".