1251391 has 4 divisors (see below), whose sum is σ = 1266552. Its totient is φ = 1236232.

The previous prime is 1251329. The next prime is 1251409. The reversal of 1251391 is 1931521.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1251391 - 2¹¹ = 1249343 is a prime.

It is a Duffinian number.

1251391 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1251301) 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 in 3 ways as a sum of consecutive naturals, for example, 7456 + ... + 7621.

It is an arithmetic number, because the mean of its divisors is an integer number (316638).

2^1251391 is an apocalyptic number.

1251391 is the 708-th centered pentagonal number.

1251391 is a deficient number, since it is larger than the sum of its proper divisors (15161).

1251391 is an equidigital number, since it uses as much as digits as its factorization.

1251391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15160.

The product of its digits is 270, while the sum is 22.

The square root of 1251391 is about 1118.6558898964. The cubic root of 1251391 is about 107.7616772712.

The spelling of 1251391 in words is "one million, two hundred fifty-one thousand, three hundred ninety-one".