21770320 has 120 divisors (see below), whose sum is σ = 60261768. Its totient is φ = 7265280.

The previous prime is 21770317. The next prime is 21770321. The reversal of 21770320 is 2307712.

It can be written as a sum of positive squares in 4 ways, for example, as 2795584 + 18974736 = 1672^2 + 4356^2 .

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a junction number, because it is equal to n+sod(n) for n = 21770291 and 21770300.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21770321) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 125754 + ... + 125926.

Almost surely, 2^21770320 is an apocalyptic number.

21770320 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 21770320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30130884).

21770320 is an abundant number, since it is smaller than the sum of its proper divisors (38491448).

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

21770320 is a wasteful number, since it uses less digits than its factorization.

21770320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221 (or 204 counting only the distinct ones).

The product of its (nonzero) digits is 588, while the sum is 22.

The square root of 21770320 is about 4665.8675506276. The cubic root of 21770320 is about 279.2254101771.

The spelling of 21770320 in words is "twenty-one million, seven hundred seventy thousand, three hundred twenty".