2109681 has 12 divisors (see below), whose sum is σ = 3482752. Its totient is φ = 1205496.

The previous prime is 2109671. The next prime is 2109697. The reversal of 2109681 is 1869012.

It is not a de Polignac number, because 2109681 - 2⁶ = 2109617 is a prime.

It is a super-2 number, since 2×2109681² = 8901507843522, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (2109641) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16681 + ... + 16806.

2^2109681 is an apocalyptic number.

2109681 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

2109681 is a deficient number, since it is larger than the sum of its proper divisors (1373071).

2109681 is a wasteful number, since it uses less digits than its factorization.

2109681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33500 (or 33497 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 27.

The square root of 2109681 is about 1452.4740961546. The cubic root of 2109681 is about 128.2543972137.

The spelling of 2109681 in words is "two million, one hundred nine thousand, six hundred eighty-one".