21959220 has 48 divisors (see below), whose sum is σ = 61951680. Its totient is φ = 5811456.

The previous prime is 21959213. The next prime is 21959221. The reversal of 21959220 is 2295912.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21959221) by changing a digit.

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, 7024 + ... + 9656.

It is an arithmetic number, because the mean of its divisors is an integer number (1290660).

Almost surely, 2^21959220 is an apocalyptic number.

21959220 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 21959220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30975840).

21959220 is an abundant number, since it is smaller than the sum of its proper divisors (39992460).

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

21959220 is a wasteful number, since it uses less digits than its factorization.

21959220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2784 (or 2782 counting only the distinct ones).

The product of its (nonzero) digits is 3240, while the sum is 30.

The square root of 21959220 is about 4686.0665808330. The cubic root of 21959220 is about 280.0306939141.

The spelling of 21959220 in words is "twenty-one million, nine hundred fifty-nine thousand, two hundred twenty".