21275940 has 96 divisors (see below), whose sum is σ = 68705280. Its totient is φ = 4818816.

The previous prime is 21275909. The next prime is 21275941. The reversal of 21275940 is 4957212.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 21275898 and 21275907.

It is not an unprimeable number, because it can be changed into a prime (21275941) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 75039 + ... + 75321.

It is an arithmetic number, because the mean of its divisors is an integer number (715680).

Almost surely, 2^21275940 is an apocalyptic number.

21275940 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 21275940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34352640).

21275940 is an abundant number, since it is smaller than the sum of its proper divisors (47429340).

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

21275940 is a wasteful number, since it uses less digits than its factorization.

21275940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 481 (or 479 counting only the distinct ones).

The product of its (nonzero) digits is 5040, while the sum is 30.

The square root of 21275940 is about 4612.5849585672. The cubic root of 21275940 is about 277.0955718993.

The spelling of 21275940 in words is "twenty-one million, two hundred seventy-five thousand, nine hundred forty".