2159781 has 16 divisors (see below), whose sum is σ = 3144960. Its totient is φ = 1310400.

The previous prime is 2159779. The next prime is 2159783. The reversal of 2159781 is 1879512.

It is an interprime number because it is at equal distance from previous prime (2159779) and next prime (2159783).

It is not a de Polignac number, because 2159781 - 2¹ = 2159779 is a prime.

It is a super-2 number, since 2×2159781² = 9329307935922, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2159783) 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, 2731 + ... + 3431.

It is an arithmetic number, because the mean of its divisors is an integer number (196560).

2^2159781 is an apocalyptic number.

It is an amenable number.

2159781 is a deficient number, since it is larger than the sum of its proper divisors (985179).

2159781 is a wasteful number, since it uses less digits than its factorization.

2159781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 796.

The product of its digits is 5040, while the sum is 33.

The square root of 2159781 is about 1469.6193384683. The cubic root of 2159781 is about 129.2617125395.

The spelling of 2159781 in words is "two million, one hundred fifty-nine thousand, seven hundred eighty-one".