1251765 has 12 divisors (see below), whose sum is σ = 2169804. Its totient is φ = 667584.

The previous prime is 1251743. The next prime is 1251787. The reversal of 1251765 is 5671521.

It is an interprime number because it is at equal distance from previous prime (1251743) and next prime (1251787).

It can be written as a sum of positive squares in 2 ways, for example, as 576081 + 675684 = 759^2 + 822^2 .

It is a de Polignac number, because none of the positive numbers 2^k-1251765 is a prime.

It is a congruent number.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 13864 + ... + 13953.

It is an arithmetic number, because the mean of its divisors is an integer number (180817).

2^1251765 is an apocalyptic number.

1251765 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1251765 is a deficient number, since it is larger than the sum of its proper divisors (918039).

1251765 is a wasteful number, since it uses less digits than its factorization.

1251765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27828 (or 27825 counting only the distinct ones).

The product of its digits is 2100, while the sum is 27.

The square root of 1251765 is about 1118.8230423083. The cubic root of 1251765 is about 107.7724116867.

It can be divided in two parts, 1251 and 765, that added together give a triangular number (2016 = T₆₃).

The spelling of 1251765 in words is "one million, two hundred fifty-one thousand, seven hundred sixty-five".