1211820 has 48 divisors (see below), whose sum is σ = 3575040. Its totient is φ = 305856.

The previous prime is 1211813. The next prime is 1211827. The reversal of 1211820 is 281121.

It is an interprime number because it is at equal distance from previous prime (1211813) and next prime (1211827).

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 1211820.

It is not an unprimeable number, because it can be changed into a prime (1211827) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 609 + ... + 1671.

It is an arithmetic number, because the mean of its divisors is an integer number (74480).

2^1211820 is an apocalyptic number.

1211820 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 1211820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1787520).

1211820 is an abundant number, since it is smaller than the sum of its proper divisors (2363220).

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

1211820 is a wasteful number, since it uses less digits than its factorization.

1211820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1094 (or 1092 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 15.

The square root of 1211820 is about 1100.8269618791. The cubic root of 1211820 is about 106.6136238010.

Adding to 1211820 its reverse (281121), we get a palindrome (1492941).

The spelling of 1211820 in words is "one million, two hundred eleven thousand, eight hundred twenty".