21829940 has 48 divisors (see below), whose sum is σ = 50791104. Its totient is φ = 7814400.

The previous prime is 21829933. The next prime is 21829961. The reversal of 21829940 is 4992812.

It is a self number, because there is not a number n which added to its sum of digits gives 21829940.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14000 + ... + 15480.

It is an arithmetic number, because the mean of its divisors is an integer number (1058148).

Almost surely, 2^21829940 is an apocalyptic number.

21829940 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 21829940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25395552).

21829940 is an abundant number, since it is smaller than the sum of its proper divisors (28961164).

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

21829940 is a wasteful number, since it uses less digits than its factorization.

21829940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1568 (or 1566 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 35.

The square root of 21829940 is about 4672.2521336075. The cubic root of 21829940 is about 279.4800725678.

The spelling of 21829940 in words is "twenty-one million, eight hundred twenty-nine thousand, nine hundred forty".