21666044440 has 32 divisors (see below), whose sum is σ = 49335940080. Its totient is φ = 8562001792.

The previous prime is 21666044401. The next prime is 21666044447. The reversal of 21666044440 is 4444066612.

It is a self number, because there is not a number n which added to its sum of digits gives 21666044440.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21666044447) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3259639 + ... + 3266278.

Almost surely, 2^21666044440 is an apocalyptic number.

21666044440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21666044440 is an abundant number, since it is smaller than the sum of its proper divisors (27669895640).

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

21666044440 is a wasteful number, since it uses less digits than its factorization.

21666044440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6526011 (or 6526007 counting only the distinct ones).

The product of its (nonzero) digits is 110592, while the sum is 37.

The spelling of 21666044440 in words is "twenty-one billion, six hundred sixty-six million, forty-four thousand, four hundred forty".