1155421100 has 72 divisors (see below), whose sum is σ = 2623665408. Its totient is φ = 440827200.

The previous prime is 1155421093. The next prime is 1155421153. The reversal of 1155421100 is 11245511.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1588937 + ... + 1589663.

Almost surely, 2^1155421100 is an apocalyptic number.

1155421100 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 1155421100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1311832704).

1155421100 is an abundant number, since it is smaller than the sum of its proper divisors (1468244308).

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

1155421100 is a wasteful number, since it uses less digits than its factorization.

1155421100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1455 (or 1448 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 20.

The square root of 1155421100 is about 33991.4856986275. The cubic root of 1155421100 is about 1049.3332426048. Note that the first 3 decimals are identical.

Adding to 1155421100 its reverse (11245511), we get a palindrome (1166666611).

The spelling of 1155421100 in words is "one billion, one hundred fifty-five million, four hundred twenty-one thousand, one hundred".