21821850 has 72 divisors (see below), whose sum is σ = 59540832. Its totient is φ = 5728800.

The previous prime is 21821843. The next prime is 21821857. The reversal of 21821850 is 5812812.

It is an interprime number because it is at equal distance from previous prime (21821843) and next prime (21821857).

It is not an unprimeable number, because it can be changed into a prime (21821857) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 31609 + ... + 32291.

It is an arithmetic number, because the mean of its divisors is an integer number (826956).

Almost surely, 2^21821850 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21821850, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29770416).

21821850 is an abundant number, since it is smaller than the sum of its proper divisors (37718982).

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

21821850 is a wasteful number, since it uses less digits than its factorization.

21821850 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 772 (or 764 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 27.

The square root of 21821850 is about 4671.3863038717. The cubic root of 21821850 is about 279.4455439472.

The spelling of 21821850 in words is "twenty-one million, eight hundred twenty-one thousand, eight hundred fifty".