2191951 has 2 divisors, whose sum is σ = 2191952. Its totient is φ = 2191950.

The previous prime is 2191949. The next prime is 2191957. The reversal of 2191951 is 1591912.

2191951 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 2191951 - 2¹ = 2191949 is a prime.

Together with 2191949, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2191957) 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, 1095975 + 1095976.

It is an arithmetic number, because the mean of its divisors is an integer number (1095976).

2^2191951 is an apocalyptic number.

2191951 is a deficient number, since it is larger than the sum of its proper divisors (1).

2191951 is an equidigital number, since it uses as much as digits as its factorization.

2191951 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 810, while the sum is 28.

The square root of 2191951 is about 1480.5238937619. The cubic root of 2191951 is about 129.9003378165.

The spelling of 2191951 in words is "two million, one hundred ninety-one thousand, nine hundred fifty-one".