1866396729 has 4 divisors (see below), whose sum is σ = 2488528976. Its totient is φ = 1244264484.

The previous prime is 1866396713. The next prime is 1866396739. The reversal of 1866396729 is 9276936681.

It is a happy number.

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: 9276936681 = 3 ⋅3092312227.

It is not a de Polignac number, because 1866396729 - 2⁴ = 1866396713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1866396739) 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, 311066119 + ... + 311066124.

It is an arithmetic number, because the mean of its divisors is an integer number (622132244).

Almost surely, 2^1866396729 is an apocalyptic number.

It is an amenable number.

1866396729 is a deficient number, since it is larger than the sum of its proper divisors (622132247).

1866396729 is an equidigital number, since it uses as much as digits as its factorization.

1866396729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 622132246.

The product of its digits is 5878656, while the sum is 57.

The square root of 1866396729 is about 43201.8139549718. The cubic root of 1866396729 is about 1231.2171460257.

The spelling of 1866396729 in words is "one billion, eight hundred sixty-six million, three hundred ninety-six thousand, seven hundred twenty-nine".