1366747821 has 6 divisors (see below), whose sum is σ = 1974191310. Its totient is φ = 911165208.

The previous prime is 1366747801. The next prime is 1366747849. The reversal of 1366747821 is 1287476631.

It can be written as a sum of positive squares in only one way, i.e., 1332980100 + 33767721 = 36510^2 + 5811^2 .

It is not a de Polignac number, because 1366747821 - 2¹⁸ = 1366485677 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1366747801) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 75930426 + ... + 75930443.

It is an arithmetic number, because the mean of its divisors is an integer number (329031885).

Almost surely, 2^1366747821 is an apocalyptic number.

It is an amenable number.

1366747821 is a deficient number, since it is larger than the sum of its proper divisors (607443489).

1366747821 is a wasteful number, since it uses less digits than its factorization.

1366747821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151860875 (or 151860872 counting only the distinct ones).

The product of its digits is 338688, while the sum is 45.

The square root of 1366747821 is about 36969.5526210421. The cubic root of 1366747821 is about 1109.7610125858.

The spelling of 1366747821 in words is "one billion, three hundred sixty-six million, seven hundred forty-seven thousand, eight hundred twenty-one".