2109721389 has 16 divisors (see below), whose sum is σ = 2928574272. Its totient is φ = 1349716608.

The previous prime is 2109721381. The next prime is 2109721421. The reversal of 2109721389 is 9831279012.

It is not a de Polignac number, because 2109721389 - 2³ = 2109721381 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 2109721389.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2109721381) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 122079 + ... + 138284.

It is an arithmetic number, because the mean of its divisors is an integer number (183035892).

Almost surely, 2^2109721389 is an apocalyptic number.

It is an amenable number.

2109721389 is a deficient number, since it is larger than the sum of its proper divisors (818852883).

2109721389 is a wasteful number, since it uses less digits than its factorization.

2109721389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 260476.

The product of its (nonzero) digits is 54432, while the sum is 42.

The square root of 2109721389 is about 45931.7035281732. The cubic root of 2109721389 is about 1282.5521566818.

It can be divided in two parts, 21097 and 21389, that added together give a triangular number (42486 = T₂₉₁).

The spelling of 2109721389 in words is "two billion, one hundred nine million, seven hundred twenty-one thousand, three hundred eighty-nine".