1661278327 has 4 divisors (see below), whose sum is σ = 1669151896. Its totient is φ = 1653404760.

The previous prime is 1661278277. The next prime is 1661278337. The reversal of 1661278327 is 7238721661.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1661278327 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661278337) 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, 3936468 + ... + 3936889.

It is an arithmetic number, because the mean of its divisors is an integer number (417287974).

Almost surely, 2^1661278327 is an apocalyptic number.

1661278327 is a deficient number, since it is larger than the sum of its proper divisors (7873569).

1661278327 is an equidigital number, since it uses as much as digits as its factorization.

1661278327 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7873568.

The product of its digits is 169344, while the sum is 43.

The square root of 1661278327 is about 40758.7822070287. The cubic root of 1661278327 is about 1184.3520054451.

Adding to 1661278327 its reverse (7238721661), we get a palindrome (8899999988).

The spelling of 1661278327 in words is "one billion, six hundred sixty-one million, two hundred seventy-eight thousand, three hundred twenty-seven".