1216312553 has 4 divisors (see below), whose sum is σ = 1236928080. Its totient is φ = 1195697028.

The previous prime is 1216312543. The next prime is 1216312567. The reversal of 1216312553 is 3552136121.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 3552136121 = 3253 ⋅1091957.

It is a cyclic number.

It is not a de Polignac number, because 1216312553 - 2²⁸ = 947877097 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1216312543) 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, 10307675 + ... + 10307792.

It is an arithmetic number, because the mean of its divisors is an integer number (309232020).

Almost surely, 2^1216312553 is an apocalyptic number.

It is an amenable number.

1216312553 is a deficient number, since it is larger than the sum of its proper divisors (20615527).

1216312553 is an equidigital number, since it uses as much as digits as its factorization.

1216312553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20615526.

The product of its digits is 5400, while the sum is 29.

The square root of 1216312553 is about 34875.6727963777. The cubic root of 1216312553 is about 1067.4521008807.

Adding to 1216312553 its reverse (3552136121), we get a palindrome (4768448674).

The spelling of 1216312553 in words is "one billion, two hundred sixteen million, three hundred twelve thousand, five hundred fifty-three".