1621620 has 240 divisors, whose sum is σ = 6830208. Its totient is φ = 311040.

The previous prime is 1621619. The next prime is 1621621. The reversal of 1621620 is 261261.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (1621619) and next prime (1621621).

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

It is a junction number, because it is equal to n+sod(n) for n = 1621593 and 1621602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1621621) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 124734 + ... + 124746.

2^1621620 is an apocalyptic number.

1621620 is a gapful number since it is divisible by the number (10) 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 1621620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3415104).

1621620 is an abundant number, since it is smaller than the sum of its proper divisors (5208588).

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

1621620 is a wasteful number, since it uses less digits than its factorization.

1621620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52 (or 41 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 1621620 is about 1273.4284432193. The cubic root of 1621620 is about 117.4851648692.

Adding to 1621620 its reverse (261261), we get a palindrome (1882881).

The spelling of 1621620 in words is "one million, six hundred twenty-one thousand, six hundred twenty".