1231665 has 16 divisors (see below), whose sum is σ = 1987008. Its totient is φ = 651456.

The previous prime is 1231663. The next prime is 1231669. The reversal of 1231665 is 5661321.

1231665 is a nontrivial binomial coefficient, being equal to C(1570, 2).

It is not a de Polignac number, because 1231665 - 2¹ = 1231663 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1231663) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2094 + ... + 2616.

It is an arithmetic number, because the mean of its divisors is an integer number (124188).

2^1231665 is an apocalyptic number.

1231665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1231665 is the 1569-th triangular number and also the 785-th hexagonal number.

It is an amenable number.

1231665 is a deficient number, since it is larger than the sum of its proper divisors (755343).

1231665 is a wasteful number, since it uses less digits than its factorization.

1231665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 688.

The product of its digits is 1080, while the sum is 24.

The square root of 1231665 is about 1109.8040367560. The cubic root of 1231665 is about 107.1924506917.

Adding to 1231665 its reverse (5661321), we get a palindrome (6892986).

The spelling of 1231665 in words is "one million, two hundred thirty-one thousand, six hundred sixty-five".