1261891 has 2 divisors, whose sum is σ = 1261892. Its totient is φ = 1261890.

The previous prime is 1261889. The next prime is 1261901. The reversal of 1261891 is 1981621.

It is a happy number.

It is a weak prime.

It is an emirp because it is prime and its reverse (1981621) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1261891 - 2¹ = 1261889 is a prime.

Together with 1261889, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1261801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 630945 + 630946.

It is an arithmetic number, because the mean of its divisors is an integer number (630946).

2^1261891 is an apocalyptic number.

1261891 is a deficient number, since it is larger than the sum of its proper divisors (1).

1261891 is an equidigital number, since it uses as much as digits as its factorization.

1261891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 864, while the sum is 28.

The square root of 1261891 is about 1123.3392185800. The cubic root of 1261891 is about 108.0622355059.

The spelling of 1261891 in words is "one million, two hundred sixty-one thousand, eight hundred ninety-one".