1221620 has 24 divisors (see below), whose sum is σ = 2717064. Its totient is φ = 459776.

The previous prime is 1221601. The next prime is 1221631. The reversal of 1221620 is 261221.

It can be written as a sum of positive squares in 4 ways, for example, as 164836 + 1056784 = 406^2 + 1028^2 .

It is a junction number, because it is equal to n+sod(n) for n = 1221595 and 1221604.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1457 + ... + 2136.

It is an arithmetic number, because the mean of its divisors is an integer number (113211).

2^1221620 is an apocalyptic number.

1221620 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221620 is an abundant number, since it is smaller than the sum of its proper divisors (1495444).

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

1221620 is a wasteful number, since it uses less digits than its factorization.

1221620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3619 (or 3617 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 1221620 is about 1105.2691979785. The cubic root of 1221620 is about 106.9002476744.

Adding to 1221620 its reverse (261221), we get a palindrome (1482841).

The spelling of 1221620 in words is "one million, two hundred twenty-one thousand, six hundred twenty".