1221688 has 32 divisors (see below), whose sum is σ = 2615760. Its totient is φ = 529920.

The previous prime is 1221667. The next prime is 1221707. The reversal of 1221688 is 8861221.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1423 + ... + 2113.

2^1221688 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 1221688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1307880).

1221688 is an abundant number, since it is smaller than the sum of its proper divisors (1394072).

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

1221688 is a wasteful number, since it uses less digits than its factorization.

1221688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 727 (or 723 counting only the distinct ones).

The product of its digits is 1536, while the sum is 28.

The square root of 1221688 is about 1105.2999592871. The cubic root of 1221688 is about 106.9022311286.

It can be divided in two parts, 1221 and 688, that multiplied together give a palindrome (840048).

The spelling of 1221688 in words is "one million, two hundred twenty-one thousand, six hundred eighty-eight".