21540750 has 128 divisors (see below), whose sum is σ = 67212288. Its totient is φ = 4464000.

The previous prime is 21540731. The next prime is 21540763. The reversal of 21540750 is 5704512.

It is a self number, because there is not a number n which added to its sum of digits gives 21540750.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 57564 + ... + 57936.

It is an arithmetic number, because the mean of its divisors is an integer number (525096).

Almost surely, 2^21540750 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21540750, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33606144).

21540750 is an abundant number, since it is smaller than the sum of its proper divisors (45671538).

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

21540750 is a wasteful number, since it uses less digits than its factorization.

21540750 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 411 (or 401 counting only the distinct ones).

The product of its (nonzero) digits is 1400, while the sum is 24.

The square root of 21540750 is about 4641.2013530981. The cubic root of 21540750 is about 278.2404541075.

The spelling of 21540750 in words is "twenty-one million, five hundred forty thousand, seven hundred fifty".