621720 has 96 divisors (see below), whose sum is σ = 2218320. Its totient is φ = 149760.

The previous prime is 621703. The next prime is 621721. The reversal of 621720 is 27126.

It is a happy number.

621720 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a nialpdrome in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 621693 and 621702.

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 621720.

It is not an unprimeable number, because it can be changed into a prime (621721) by changing a digit.

621720 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 23 ways as a sum of consecutive naturals, for example, 3882 + ... + 4038.

2⁶²¹⁷²⁰ is an apocalyptic number.

621720 is a gapful number since it is divisible by the number (60) 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 621720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1109160).

621720 is an abundant number, since it is smaller than the sum of its proper divisors (1596600).

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

621720 is a wasteful number, since it uses less digits than its factorization.

621720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 185 (or 178 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 18.

The square root of 621720 is about 788.4922320480. The cubic root of 621720 is about 85.3489690316.

Adding to 621720 its reverse (27126), we get a palindrome (648846).

The spelling of 621720 in words is "six hundred twenty-one thousand, seven hundred twenty".