9721620 has 120 divisors (see below), whose sum is σ = 32382504. Its totient is φ = 2433024.

The previous prime is 9721609. The next prime is 9721643. The reversal of 9721620 is 261279.

It can be written as a sum of positive squares in 4 ways, for example, as 1633284 + 8088336 = 1278^2 + 2844^2 .

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 27364 + ... + 27716.

Almost surely, 2^9721620 is an apocalyptic number.

9721620 is a gapful number since it is divisible by the number (90) 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 9721620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (16191252).

9721620 is an abundant number, since it is smaller than the sum of its proper divisors (22660884).

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

9721620 is a wasteful number, since it uses less digits than its factorization.

9721620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 391 (or 380 counting only the distinct ones).

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

The square root of 9721620 is about 3117.9512504207. The cubic root of 9721620 is about 213.4254539218.

Adding to 9721620 its reverse (261279), we get a palindrome (9982899).

The spelling of 9721620 in words is "nine million, seven hundred twenty-one thousand, six hundred twenty".