1221500 has 48 divisors (see below), whose sum is σ = 3057600. Its totient is φ = 417600.

The previous prime is 1221499. The next prime is 1221503. The reversal of 1221500 is 51221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221503) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 3326 + ... + 3674.

It is an arithmetic number, because the mean of its divisors is an integer number (63700).

2^1221500 is an apocalyptic number.

1221500 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 1221500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1528800).

1221500 is an abundant number, since it is smaller than the sum of its proper divisors (1836100).

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

1221500 is a wasteful number, since it uses less digits than its factorization.

1221500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 375 (or 363 counting only the distinct ones).

The product of its (nonzero) digits is 20, while the sum is 11.

The square root of 1221500 is about 1105.2149112277. The cubic root of 1221500 is about 106.8967472816.

1221500 divided by its product of nonzero digits (20) gives a triangular number (61075 = T₃₄₉).

Adding to 1221500 its reverse (51221), we get a palindrome (1272721).

It can be divided in two parts, 12 and 21500, that added together give a palindrome (21512).

The spelling of 1221500 in words is "one million, two hundred twenty-one thousand, five hundred".