21940380 has 144 divisors (see below), whose sum is σ = 83026944. Its totient is φ = 4556160.

The previous prime is 21940313. The next prime is 21940381. The reversal of 21940380 is 8304912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21940381) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 13069 + ... + 14651.

It is an arithmetic number, because the mean of its divisors is an integer number (576576).

Almost surely, 2^21940380 is an apocalyptic number.

21940380 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 21940380, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41513472).

21940380 is an abundant number, since it is smaller than the sum of its proper divisors (61086564).

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

21940380 is a wasteful number, since it uses less digits than its factorization.

21940380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1616 (or 1611 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 21940380 is about 4684.0559347642. The cubic root of 21940380 is about 279.9505865183.

The spelling of 21940380 in words is "twenty-one million, nine hundred forty thousand, three hundred eighty".