1221005749365 has 12 divisors (see below), whose sum is σ = 2116409965644. Its totient is φ = 651203066304.

The previous prime is 1221005749363. The next prime is 1221005749417. The reversal of 1221005749365 is 5639475001221.

1221005749365 is a `hidden beast` number, since 1 + 2 + 2 + 10 + 0 + 574 + 9 + 3 + 65 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 133611449841 + 1087394299524 = 365529^2 + 1042782^2 .

It is not a de Polignac number, because 1221005749365 - 2¹ = 1221005749363 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45), and also a Moran number because the ratio is a prime number: 27133461097 = 1221005749365 / (1 + 2 + 2 + 1 + 0 + 0 + 5 + 7 + 4 + 9 + 3 + 6 + 5).

It is a self number, because there is not a number n which added to its sum of digits gives 1221005749365.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221005749363) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 13566730504 + ... + 13566730593.

It is an arithmetic number, because the mean of its divisors is an integer number (176367497137).

Almost surely, 2^{1221005749365} is an apocalyptic number.

1221005749365 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1221005749365 is a deficient number, since it is larger than the sum of its proper divisors (895404216279).

1221005749365 is a wasteful number, since it uses less digits than its factorization.

1221005749365 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27133461108 (or 27133461105 counting only the distinct ones).

The product of its (nonzero) digits is 453600, while the sum is 45.

The spelling of 1221005749365 in words is "one trillion, two hundred twenty-one billion, five million, seven hundred forty-nine thousand, three hundred sixty-five".