21667140 has 144 divisors (see below), whose sum is σ = 74221056. Its totient is φ = 5068800.

The previous prime is 21667123. The next prime is 21667153. The reversal of 21667140 is 4176612.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 61204 + ... + 61556.

It is an arithmetic number, because the mean of its divisors is an integer number (515424).

Almost surely, 2^21667140 is an apocalyptic number.

21667140 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 21667140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37110528).

21667140 is an abundant number, since it is smaller than the sum of its proper divisors (52553916).

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

21667140 is a wasteful number, since it uses less digits than its factorization.

21667140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 410 (or 405 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 21667140 is about 4654.7975251347. The cubic root of 21667140 is about 278.7835836658.

The spelling of 21667140 in words is "twenty-one million, six hundred sixty-seven thousand, one hundred forty".