1971091 has 2 divisors, whose sum is σ = 1971092. Its totient is φ = 1971090.

The previous prime is 1971049. The next prime is 1971107. The reversal of 1971091 is 1901791.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1971091 - 2¹⁷ = 1840019 is a prime.

1971091 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (1971691) 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, 985545 + 985546.

It is an arithmetic number, because the mean of its divisors is an integer number (985546).

2^1971091 is an apocalyptic number.

1971091 is a deficient number, since it is larger than the sum of its proper divisors (1).

1971091 is an equidigital number, since it uses as much as digits as its factorization.

1971091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 567, while the sum is 28.

The square root of 1971091 is about 1403.9554836247. The cubic root of 1971091 is about 125.3821054400.

The spelling of 1971091 in words is "one million, nine hundred seventy-one thousand, ninety-one".