21940128 has 72 divisors (see below), whose sum is σ = 71311968. Its totient is φ = 6268032.

The previous prime is 21940111. The next prime is 21940151. The reversal of 21940128 is 82104912.

It is a tau number, because it is divible by the number of its divisors (72).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3426 + ... + 7457.

It is an arithmetic number, because the mean of its divisors is an integer number (990444).

Almost surely, 2^21940128 is an apocalyptic number.

21940128 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21940128 is an abundant number, since it is smaller than the sum of its proper divisors (49371840).

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

21940128 is a wasteful number, since it uses less digits than its factorization.

21940128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10906 (or 10895 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 21940128 is about 4684.0290349228. The cubic root of 21940128 is about 279.9495147073.

The spelling of 21940128 in words is "twenty-one million, nine hundred forty thousand, one hundred twenty-eight".