1213021900 has 72 divisors (see below), whose sum is σ = 2712326400. Its totient is φ = 470592000.

The previous prime is 1213021877. The next prime is 1213021903. The reversal of 1213021900 is 91203121.

It is a super-2 number, since 2×1213021900² = 2942844259759220000, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1213021903) 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, 782326 + ... + 783874.

It is an arithmetic number, because the mean of its divisors is an integer number (37671200).

Almost surely, 2^1213021900 is an apocalyptic number.

1213021900 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 1213021900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1356163200).

1213021900 is an abundant number, since it is smaller than the sum of its proper divisors (1499304500).

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

1213021900 is a wasteful number, since it uses less digits than its factorization.

1213021900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1795 (or 1788 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 19.

The square root of 1213021900 is about 34828.4639339722. The cubic root of 1213021900 is about 1066.4885911494.

The spelling of 1213021900 in words is "one billion, two hundred thirteen million, twenty-one thousand, nine hundred".