21960720 has 100 divisors (see below), whose sum is σ = 76295340. Its totient is φ = 5854464.

The previous prime is 21960683. The next prime is 21960727. The reversal of 21960720 is 2706912.

It can be written as a sum of positive squares in 2 ways, for example, as 15968016 + 5992704 = 3996^2 + 2448^2 .

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21960727) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 4786 + ... + 8174.

Almost surely, 2^21960720 is an apocalyptic number.

21960720 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 21960720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38147670).

21960720 is an abundant number, since it is smaller than the sum of its proper divisors (54334620).

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

21960720 is a wasteful number, since it uses less digits than its factorization.

21960720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3414 (or 3399 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 27.

The square root of 21960720 is about 4686.2266270423. The cubic root of 21960720 is about 280.0370699219.

The spelling of 21960720 in words is "twenty-one million, nine hundred sixty thousand, seven hundred twenty".