1213503541665 has 16 divisors (see below), whose sum is σ = 1959751516608. Its totient is φ = 641153272256.

The previous prime is 1213503541633. The next prime is 1213503541681. The reversal of 1213503541665 is 5661453053121.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 1213503541665 - 2⁵ = 1213503541633 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 378036882 + ... + 378040091.

It is an arithmetic number, because the mean of its divisors is an integer number (122484469788).

Almost surely, 2^{1213503541665} is an apocalyptic number.

1213503541665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1213503541665 is a deficient number, since it is larger than the sum of its proper divisors (746247974943).

1213503541665 is a wasteful number, since it uses less digits than its factorization.

1213503541665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 756077088.

The product of its (nonzero) digits is 324000, while the sum is 42.

Adding to 1213503541665 its reverse (5661453053121), we get a palindrome (6874956594786).

The spelling of 1213503541665 in words is "one trillion, two hundred thirteen billion, five hundred three million, five hundred forty-one thousand, six hundred sixty-five".