21959730 has 72 divisors (see below), whose sum is σ = 61939332. Its totient is φ = 5366016.

The previous prime is 21959689. The next prime is 21959761. The reversal of 21959730 is 3795912.

It can be written as a sum of positive squares in 6 ways, for example, as 7144929 + 14814801 = 2673^2 + 3849^2 .

It is a Curzon 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 35 ways as a sum of consecutive naturals, for example, 160222 + ... + 160358.

Almost surely, 2^21959730 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21959730, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30969666).

21959730 is an abundant number, since it is smaller than the sum of its proper divisors (39979602).

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

21959730 is a wasteful number, since it uses less digits than its factorization.

21959730 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 300 (or 160 counting only the distinct ones).

The product of its (nonzero) digits is 17010, while the sum is 36.

The square root of 21959730 is about 4686.1209971575. The cubic root of 21959730 is about 280.0328617893.

The spelling of 21959730 in words is "twenty-one million, nine hundred fifty-nine thousand, seven hundred thirty".