1611212220 has 72 divisors (see below), whose sum is σ = 4898152896. Its totient is φ = 428706432.

The previous prime is 1611212209. The next prime is 1611212227. The reversal of 1611212220 is 222121161.

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

It is a junction number, because it is equal to n+sod(n) for n = 1611212193 and 1611212202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1611212227) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 73674 + ... + 93006.

Almost surely, 2^1611212220 is an apocalyptic number.

1611212220 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 1611212220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2449076448).

1611212220 is an abundant number, since it is smaller than the sum of its proper divisors (3286940676).

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

1611212220 is a wasteful number, since it uses less digits than its factorization.

1611212220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19811 (or 19806 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 1611212220 is about 40139.9080716436. The cubic root of 1611212220 is about 1172.3327990978.

Adding to 1611212220 its reverse (222121161), we get a palindrome (1833333381).

The spelling of 1611212220 in words is "one billion, six hundred eleven million, two hundred twelve thousand, two hundred twenty".