2159981 has 4 divisors (see below), whose sum is σ = 2163264. Its totient is φ = 2156700.

The previous prime is 2159959. The next prime is 2160001. The reversal of 2159981 is 1899512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2159981 is a prime.

It is a super-2 number, since 2×2159981² = 9331035840722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2159951) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 275 + ... + 2096.

It is an arithmetic number, because the mean of its divisors is an integer number (540816).

2^2159981 is an apocalyptic number.

It is an amenable number.

2159981 is a deficient number, since it is larger than the sum of its proper divisors (3283).

2159981 is an equidigital number, since it uses as much as digits as its factorization.

2159981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3282.

The product of its digits is 6480, while the sum is 35.

The square root of 2159981 is about 1469.6873817244. The cubic root of 2159981 is about 129.2657023799.

The spelling of 2159981 in words is "two million, one hundred fifty-nine thousand, nine hundred eighty-one".