1216523100 has 144 divisors (see below), whose sum is σ = 3843385952. Its totient is φ = 295280640.

The previous prime is 1216523071. The next prime is 1216523123. The reversal of 1216523100 is 13256121.

It is a super-2 number, since 2×1216523100² = 2959856905667220000, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 282564 + ... + 286836.

Almost surely, 2^1216523100 is an apocalyptic number.

1216523100 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 1216523100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1921692976).

1216523100 is an abundant number, since it is smaller than the sum of its proper divisors (2626862852).

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

1216523100 is a wasteful number, since it uses less digits than its factorization.

1216523100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4376 (or 4369 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 21.

The square root of 1216523100 is about 34878.6912025093. The cubic root of 1216523100 is about 1067.5136902778.

Adding to 1216523100 its reverse (13256121), we get a palindrome (1229779221).

The spelling of 1216523100 in words is "one billion, two hundred sixteen million, five hundred twenty-three thousand, one hundred".