2191961 has 4 divisors (see below), whose sum is σ = 2195892. Its totient is φ = 2188032.

The previous prime is 2191957. The next prime is 2191967. The reversal of 2191961 is 1691912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1336336 + 855625 = 1156^2 + 925^2 .

It is a cyclic number.

It is not a de Polignac number, because 2191961 - 2² = 2191957 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (2191967) 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, 956 + ... + 2301.

It is an arithmetic number, because the mean of its divisors is an integer number (548973).

2^2191961 is an apocalyptic number.

It is an amenable number.

2191961 is a deficient number, since it is larger than the sum of its proper divisors (3931).

2191961 is an equidigital number, since it uses as much as digits as its factorization.

2191961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3930.

The product of its digits is 972, while the sum is 29.

The square root of 2191961 is about 1480.5272709410. The cubic root of 2191961 is about 129.9005353576.

The spelling of 2191961 in words is "two million, one hundred ninety-one thousand, nine hundred sixty-one".