1216264540681 has 4 divisors (see below), whose sum is σ = 1249136555332. Its totient is φ = 1183392526032.

The previous prime is 1216264540679. The next prime is 1216264540691. The reversal of 1216264540681 is 1860454626121.

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

It can be written as a sum of positive squares in 2 ways, for example, as 472953296656 + 743311244025 = 687716^2 + 862155^2 .

It is a cyclic number.

It is not a de Polignac number, because 1216264540681 - 2¹ = 1216264540679 is a prime.

It is a super-2 number, since 2×1216264540681² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1216264540661) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16436007270 + ... + 16436007343.

It is an arithmetic number, because the mean of its divisors is an integer number (312284138833).

Almost surely, 2^{1216264540681} is an apocalyptic number.

It is an amenable number.

1216264540681 is a deficient number, since it is larger than the sum of its proper divisors (32872014651).

1216264540681 is an equidigital number, since it uses as much as digits as its factorization.

1216264540681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32872014650.

The product of its (nonzero) digits is 552960, while the sum is 46.

The spelling of 1216264540681 in words is "one trillion, two hundred sixteen billion, two hundred sixty-four million, five hundred forty thousand, six hundred eighty-one".