1291887 has 18 divisors (see below), whose sum is σ = 1972152. Its totient is φ = 813384.

The previous prime is 1291883. The next prime is 1291907. The reversal of 1291887 is 7881921.

It is not a de Polignac number, because 1291887 - 2² = 1291883 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1291883) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 16314 + ... + 16392.

It is an arithmetic number, because the mean of its divisors is an integer number (109564).

2^1291887 is an apocalyptic number.

1291887 is a deficient number, since it is larger than the sum of its proper divisors (680265).

1291887 is an equidigital number, since it uses as much as digits as its factorization.

1291887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 187 (or 105 counting only the distinct ones).

The product of its digits is 8064, while the sum is 36.

The square root of 1291887 is about 1136.6120710251. The cubic root of 1291887 is about 108.9117766610.

It can be divided in two parts, 129 and 1887, that added together give a triangular number (2016 = T₆₃).

The spelling of 1291887 in words is "one million, two hundred ninety-one thousand, eight hundred eighty-seven".