921620 has 48 divisors (see below), whose sum is σ = 2298240. Its totient is φ = 303744.

The previous prime is 921611. The next prime is 921629. The reversal of 921620 is 26129.

921620 = T₄₇₆ + T₄₇₇ + ... + T₄₈₃.

921620 = 21² + 22² + ... + 140².

It is an interprime number because it is at equal distance from previous prime (921611) and next prime (921629).

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 921592 and 921601.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 921620.

It is not an unprimeable number, because it can be changed into a prime (921629) by changing a digit.

921620 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3947 + ... + 4173.

It is an arithmetic number, because the mean of its divisors is an integer number (47880).

2⁹²¹⁶²⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 921620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1149120).

921620 is an abundant number, since it is smaller than the sum of its proper divisors (1376620).

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

921620 is a wasteful number, since it uses less digits than its factorization.

921620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 272 (or 270 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 921620 is about 960.0104166102. The cubic root of 921620 is about 97.3159358826.

Subtracting from 921620 its sum of digits (20), we obtain a square (921600 = 960²).

Adding to 921620 its reverse (26129), we get a palindrome (947749).

The spelling of 921620 in words is "nine hundred twenty-one thousand, six hundred twenty".