1213889820 has 144 divisors (see below), whose sum is σ = 4015412352. Its totient is φ = 271614720.

The previous prime is 1213889797. The next prime is 1213889827. The reversal of 1213889820 is 289883121.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1213889827) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 106099 + ... + 116981.

It is an arithmetic number, because the mean of its divisors is an integer number (27884808).

Almost surely, 2^1213889820 is an apocalyptic number.

1213889820 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 1213889820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2007706176).

1213889820 is an abundant number, since it is smaller than the sum of its proper divisors (2801522532).

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

1213889820 is a wasteful number, since it uses less digits than its factorization.

1213889820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10932 (or 10917 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 42.

The square root of 1213889820 is about 34840.9216296010. The cubic root of 1213889820 is about 1066.7428888674.

The spelling of 1213889820 in words is "one billion, two hundred thirteen million, eight hundred eighty-nine thousand, eight hundred twenty".