1216819747645 has 4 divisors (see below), whose sum is σ = 1460183697180. Its totient is φ = 973455798112.

The previous prime is 1216819747601. The next prime is 1216819747673. The reversal of 1216819747645 is 5467479186121.

It is a happy number.

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 546744894084 + 670074853561 = 739422^2 + 818581^2 .

It is a cyclic number.

It is not a de Polignac number, because 1216819747645 - 2²³ = 1216811359037 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 121681974760 + ... + 121681974769.

It is an arithmetic number, because the mean of its divisors is an integer number (365045924295).

Almost surely, 2^{1216819747645} is an apocalyptic number.

It is an amenable number.

1216819747645 is a deficient number, since it is larger than the sum of its proper divisors (243363949535).

1216819747645 is an equidigital number, since it uses as much as digits as its factorization.

1216819747645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 243363949534.

The product of its digits is 20321280, while the sum is 61.

The spelling of 1216819747645 in words is "one trillion, two hundred sixteen billion, eight hundred nineteen million, seven hundred forty-seven thousand, six hundred forty-five".