2109721381 has 2 divisors, whose sum is σ = 2109721382. Its totient is φ = 2109721380.

The previous prime is 2109721363. The next prime is 2109721421. The reversal of 2109721381 is 1831279012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2107269025 + 2452356 = 45905^2 + 1566^2 .

It is a cyclic number.

It is not a de Polignac number, because 2109721381 - 2¹¹ = 2109719333 is a prime.

It is a super-2 number, since 2×2109721381² = 8901848610897094322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2109721321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1054860690 + 1054860691.

It is an arithmetic number, because the mean of its divisors is an integer number (1054860691).

Almost surely, 2^2109721381 is an apocalyptic number.

It is an amenable number.

2109721381 is a deficient number, since it is larger than the sum of its proper divisors (1).

2109721381 is an equidigital number, since it uses as much as digits as its factorization.

2109721381 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6048, while the sum is 34.

The square root of 2109721381 is about 45931.7034410874. The cubic root of 2109721381 is about 1282.5521550606.

The spelling of 2109721381 in words is "two billion, one hundred nine million, seven hundred twenty-one thousand, three hundred eighty-one".