1221624 has 72 divisors (see below), whose sum is σ = 3566160. Its totient is φ = 377568.

The previous prime is 1221601. The next prime is 1221631. The reversal of 1221624 is 4261221.

It is a tau number, because it is divible by the number of its divisors (72).

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

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 1221597 and 1221606.

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 17 ways as a sum of consecutive naturals, for example, 25969 + ... + 26015.

It is an arithmetic number, because the mean of its divisors is an integer number (49530).

2^1221624 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 1221624, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1783080).

1221624 is an abundant number, since it is smaller than the sum of its proper divisors (2344536).

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

1221624 is a wasteful number, since it uses less digits than its factorization.

1221624 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97 (or 71 counting only the distinct ones).

The product of its digits is 192, while the sum is 18.

The square root of 1221624 is about 1105.2710074909. The cubic root of 1221624 is about 106.9003643502.

Adding to 1221624 its reverse (4261221), we get a palindrome (5482845).

The spelling of 1221624 in words is "one million, two hundred twenty-one thousand, six hundred twenty-four".