2109121820 has 48 divisors (see below), whose sum is σ = 4801960800. Its totient is φ = 773511936.

The previous prime is 2109121799. The next prime is 2109121843. The reversal of 2109121820 is 281219012.

It is a super-2 number, since 2×2109121820² = 8896789703200224800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a self number, because there is not a number n which added to its sum of digits gives 2109121820.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11519 + ... + 65961.

It is an arithmetic number, because the mean of its divisors is an integer number (100040850).

Almost surely, 2^2109121820 is an apocalyptic number.

2109121820 is a gapful number since it is divisible by the number (20) 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 2109121820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2400980400).

2109121820 is an abundant number, since it is smaller than the sum of its proper divisors (2692838980).

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

2109121820 is a wasteful number, since it uses less digits than its factorization.

2109121820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54614 (or 54612 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 26.

The square root of 2109121820 is about 45925.1763197486. The cubic root of 2109121820 is about 1282.4306475296.

The spelling of 2109121820 in words is "two billion, one hundred nine million, one hundred twenty-one thousand, eight hundred twenty".