2155961 has 2 divisors, whose sum is σ = 2155962. Its totient is φ = 2155960.

The previous prime is 2155931. The next prime is 2155963. The reversal of 2155961 is 1695512.

2155961 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1771561 + 384400 = 1331^2 + 620^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2155961 is a prime.

Together with 2155963, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (2155963) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1077980 + 1077981.

It is an arithmetic number, because the mean of its divisors is an integer number (1077981).

2^2155961 is an apocalyptic number.

It is an amenable number.

2155961 is a deficient number, since it is larger than the sum of its proper divisors (1).

2155961 is an equidigital number, since it uses as much as digits as its factorization.

2155961 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2700, while the sum is 29.

The square root of 2155961 is about 1468.3191070064. The cubic root of 2155961 is about 129.1854592613.

The spelling of 2155961 in words is "two million, one hundred fifty-five thousand, nine hundred sixty-one".